Skip to content

Latest commit

 

History

History
1363 lines (1007 loc) · 60.9 KB

user-guide.md

File metadata and controls

1363 lines (1007 loc) · 60.9 KB
Raw

ARM Trusted Firmware User Guide

Contents :

  1. Introduction

  2. Host machine requirements

  3. Tools

  4. Getting the Trusted Firmware source code

  5. Building the Trusted Firmware

  6. Building the rest of the software stack

  7. EL3 payloads alternative boot flow

  8. Preparing the images to run on FVP

  9. Running the software on FVP

  10. Running the software on Juno

  11. Changes required for booting Linux on FVP in GICv3 mode

  12. Introduction

This document describes how to build ARM Trusted Firmware and run it with a tested set of other software components using defined configurations on the Juno ARM development platform and ARM Fixed Virtual Platform (FVP) models. It is possible to use other software components, configurations and platforms but that is outside the scope of this document.

This document should be used in conjunction with the Firmware Design and the Instructions for using the Linaro software deliverables.

  1. Host machine requirements

The minimum recommended machine specification for building the software and running the FVP models is a dual-core processor running at 2GHz with 12GB of RAM. For best performance, use a machine with a quad-core processor running at 2.6GHz with 16GB of RAM.

The software has been tested on Ubuntu 14.04 LTS (64-bit). Packages used for building the software were installed from that distribution unless otherwise specified.

  1. Tools

In addition to the mandatory prerequisite tools listed in the instructions for using the Linaro software deliverables, the following optional tools may be needed:

  • device-tree-compiler package if you need to rebuild the Flattened Device Tree (FDT) source files (.dts files) provided with this software.

  • For debugging, ARM Development Studio 5 (DS-5) v5.22.

  1. Getting the Trusted Firmware source code

The Trusted Firmware (TF) source code can be obtained as part of the standard Linaro releases, which provide a full software stack, including TF, normal world firmware, Linux kernel and device tree, file system as well as any additional micro-controller firmware required by the platform. This TF version is tested with the Linaro 15.10 Release.

Note 1: Both the LSK kernel or the latest tracking kernel can be used with TF; choose the one that best suits your needs.

Note 2: Currently to run the latest tracking kernel on FVP with GICv3 driver, some modifications are required to UEFI. Refer here for more details.

The TF source code will then be in arm-tf/. This is the upstream git repository cloned from GitHub. The revision checked out by the repo tool is indicated by the manifest file. Depending on the manifest file you're using, this might not be the latest upstream version. To synchronize your copy of the repository and get the latest updates, use the following commands:

# Change to the Trusted Firmware directory.
cd arm-tf

# Download the latest code from GitHub.
git fetch github

# Update your working copy to the latest master.
# This command will create a local branch master that tracks the remote
# branch master from GitHub.
git checkout --track github/master

Alternatively, the TF source code can be separately cloned from the upstream GitHub repository:

git clone https://github.com/ARM-software/arm-trusted-firmware.git
  1. Building the Trusted Firmware

To build the Trusted Firmware images, change to the root directory of the Trusted Firmware source tree and follow these steps:

  1. Set the compiler path, specify a Non-trusted Firmware image (BL33) and a valid platform, and then build:

    CROSS_COMPILE=<path-to-aarch64-gcc>/bin/aarch64-linux-gnu- \
BL33=<path-to>/<bl33_image>                                \
make PLAT=<platform> all fip

    If PLAT is not specified, fvp is assumed by default. See the "Summary of build options" for more information on available build options.

    The BL33 image corresponds to the software that is executed after switching to the non-secure world. UEFI can be used as the BL33 image. Refer to the "Building the rest of the software stack" section below.

    The TSP (Test Secure Payload), corresponding to the BL32 image, is not compiled in by default. Refer to the "Building the Test Secure Payload" section below.

    By default this produces a release version of the build. To produce a debug version instead, refer to the "Debugging options" section below.

    The build process creates products in a build directory tree, building the objects and binaries for each boot loader stage in separate sub-directories. The following boot loader binary files are created from the corresponding ELF files:

    • build/<platform>/<build-type>/bl1.bin
    • build/<platform>/<build-type>/bl2.bin
    • build/<platform>/<build-type>/bl31.bin

    where <platform> is the name of the chosen platform and <build-type> is either debug or release. A Firmware Image Package (FIP) will be created as part of the build. It contains all boot loader images except for bl1.bin.

    • build/<platform>/<build-type>/fip.bin

    For more information on FIPs, see the "Firmware Image Package" section in the Firmware Design.

  2. (Optional) Some platforms may require a SCP_BL2 image to boot. This image can be included in the FIP when building the Trusted Firmware by specifying the SCP_BL2 build option:

    SCP_BL2=<path-to>/<scp_bl2_image>

  3. Output binary files bl1.bin and fip.bin are both required to boot the system. How these files are used is platform specific. Refer to the platform documentation on how to use the firmware images.

  4. (Optional) Build products for a specific build variant can be removed using:

    make DEBUG=<D> PLAT=<platform> clean

    ... where <D> is 0 or 1, as specified when building.

    The build tree can be removed completely using:

    make realclean

  5. (Optional) Path to binary for certain BL stages (BL2, BL31 and BL32) can be provided by specifying the BLx=/<blx_image> where BLx is the BL stage. This will bypass the build of the BL component from source, but will include the specified binary in the final FIP image. Please note that BL32 will be included in the build, only if the SPD build option is specified.

    For example, specifying BL2=<path-to>/<bl2_image> in the build option, will skip compilation of BL2 source in trusted firmware, but include the BL2 binary specified in the final FIP image.

Summary of build options

ARM Trusted Firmware build system supports the following build options. Unless mentioned otherwise, these options are expected to be specified at the build command line and are not to be modified in any component makefiles. Note that the build system doesn't track dependency for build options. Therefore, if any of the build options are changed from a previous build, a clean build must be performed.

Common build options

  • SCP_BL2: Path to SCP_BL2 image in the host file system. This image is optional. If a SCP_BL2 image is present then this option must be passed for the fip target.

  • BL33: Path to BL33 image in the host file system. This is mandatory for fip target in case the BL2 from ARM Trusted Firmware is used.

  • BL2: This is an optional build option which specifies the path to BL2 image for the fip target. In this case, the BL2 in the ARM Trusted Firmware will not be built.

  • BL31: This is an optional build option which specifies the path to BL31 image for the fip target. In this case, the BL31 in the ARM Trusted Firmware will not be built.

  • BL32: This is an optional build option which specifies the path to BL32 image for the fip target. In this case, the BL32 in the ARM Trusted Firmware will not be built.

  • FIP_NAME: This is an optional build option which specifies the FIP filename for the fip target. Default is fip.bin.

  • FWU_FIP_NAME: This is an optional build option which specifies the FWU FIP filename for the fwu_fip target. Default is fwu_fip.bin.

  • BL2U: This is an optional build option which specifies the path to BL2U image. In this case, the BL2U in the ARM Trusted Firmware will not be built.

  • SCP_BL2U: Path to SCP_BL2U image in the host file system. This image is optional. It is only needed if the platform makefile specifies that it is required in order to build the fwu_fip target.

  • NS_BL2U: Path to NS_BL2U image in the host file system. This image is optional. It is only needed if the platform makefile specifies that it is required in order to build the fwu_fip target.

  • CROSS_COMPILE: Prefix to toolchain binaries. Please refer to examples in this document for usage.

  • DEBUG: Chooses between a debug and release build. It can take either 0 (release) or 1 (debug) as values. 0 is the default.

  • LOG_LEVEL: Chooses the log level, which controls the amount of console log output compiled into the build. This should be one of the following:

    0  (LOG_LEVEL_NONE)
10 (LOG_LEVEL_NOTICE)
20 (LOG_LEVEL_ERROR)
30 (LOG_LEVEL_WARNING)
40 (LOG_LEVEL_INFO)
50 (LOG_LEVEL_VERBOSE)

    All log output up to and including the log level is compiled into the build. The default value is 40 in debug builds and 20 in release builds.

  • NS_TIMER_SWITCH: Enable save and restore for non-secure timer register contents upon world switch. It can take either 0 (don't save and restore) or 1 (do save and restore). 0 is the default. An SPD may set this to 1 if it wants the timer registers to be saved and restored.

  • PLAT: Choose a platform to build ARM Trusted Firmware for. The chosen platform name must be subdirectory of any depth under plat/, and must contain a platform makefile named platform.mk.

  • SPD: Choose a Secure Payload Dispatcher component to be built into the Trusted Firmware. The value should be the path to the directory containing the SPD source, relative to services/spd/; the directory is expected to contain a makefile called <spd-value>.mk.

  • V: Verbose build. If assigned anything other than 0, the build commands are printed. Default is 0.

  • ARM_GIC_ARCH: Choice of ARM GIC architecture version used by the ARM Legacy GIC driver for implementing the platform GIC API. This API is used by the interrupt management framework. Default is 2 (that is, version 2.0). This build option is deprecated.

  • ARM_CCI_PRODUCT_ID: Choice of ARM CCI product used by the platform. This is used to determine the number of valid slave interfaces available in the ARM CCI driver. Default is 400 (that is, CCI-400).

  • RESET_TO_BL31: Enable BL31 entrypoint as the CPU reset vector instead of the BL1 entrypoint. It can take the value 0 (CPU reset to BL1 entrypoint) or 1 (CPU reset to BL31 entrypoint). The default value is 0.

  • CRASH_REPORTING: A non-zero value enables a console dump of processor register state when an unexpected exception occurs during execution of BL31. This option defaults to the value of DEBUG - i.e. by default this is only enabled for a debug build of the firmware.

  • ASM_ASSERTION: This flag determines whether the assertion checks within assembly source files are enabled or not. This option defaults to the value of DEBUG - that is, by default this is only enabled for a debug build of the firmware.

  • TSP_INIT_ASYNC: Choose BL32 initialization method as asynchronous or synchronous, (see "Initializing a BL32 Image" section in Firmware Design). It can take the value 0 (BL32 is initialized using synchronous method) or 1 (BL32 is initialized using asynchronous method). Default is 0.

  • USE_COHERENT_MEM: This flag determines whether to include the coherent memory region in the BL memory map or not (see "Use of Coherent memory in Trusted Firmware" section in Firmware Design). It can take the value 1 (Coherent memory region is included) or 0 (Coherent memory region is excluded). Default is 1.

  • TSP_NS_INTR_ASYNC_PREEMPT: A non zero value enables the interrupt routing model which routes non-secure interrupts asynchronously from TSP to EL3 causing immediate preemption of TSP. The EL3 is responsible for saving and restoring the TSP context in this routing model. The default routing model (when the value is 0) is to route non-secure interrupts to TSP allowing it to save its context and hand over synchronously to EL3 via an SMC.

  • TRUSTED_BOARD_BOOT: Boolean flag to include support for the Trusted Board Boot feature. When set to '1', BL1 and BL2 images include support to load and verify the certificates and images in a FIP, and BL1 includes support for the Firmware Update. The default value is '0'. Generation and inclusion of certificates in the FIP and FWU_FIP depends upon the value of the GENERATE_COT option.

  • GENERATE_COT: Boolean flag used to build and execute the cert_create tool to create certificates as per the Chain of Trust described in Trusted Board Boot. The build system then calls the fip_create tool to include the certificates in the FIP and FWU_FIP. Default value is '0'.

    Specify both TRUSTED_BOARD_BOOT=1 and GENERATE_COT=1 to include support for the Trusted Board Boot feature in the BL1 and BL2 images, to generate the corresponding certificates, and to include those certificates in the FIP and FWU_FIP.

    Note that if TRUSTED_BOARD_BOOT=0 and GENERATE_COT=1, the BL1 and BL2 images will not include support for Trusted Board Boot. The FIP will still include the corresponding certificates. This FIP can be used to verify the Chain of Trust on the host machine through other mechanisms.

    Note that if TRUSTED_BOARD_BOOT=1 and GENERATE_COT=0, the BL1 and BL2 images will include support for Trusted Board Boot, but the FIP and FWU_FIP will not include the corresponding certificates, causing a boot failure.

  • CREATE_KEYS: This option is used when GENERATE_COT=1. It tells the certificate generation tool to create new keys in case no valid keys are present or specified. Allowed options are '0' or '1'. Default is '1'.

  • SAVE_KEYS: This option is used when GENERATE_COT=1. It tells the certificate generation tool to save the keys used to establish the Chain of Trust. Allowed options are '0' or '1'. Default is '0' (do not save).

    Note: This option depends on 'CREATE_KEYS' to be enabled. If the keys already exist in disk, they will be overwritten without further notice.

  • ROT_KEY: This option is used when GENERATE_COT=1. It specifies the file that contains the ROT private key in PEM format. If SAVE_KEYS=1, this file name will be used to save the key.

  • TRUSTED_WORLD_KEY: This option is used when GENERATE_COT=1. It specifies the file that contains the Trusted World private key in PEM format. If SAVE_KEYS=1, this file name will be used to save the key.

  • NON_TRUSTED_WORLD_KEY: This option is used when GENERATE_COT=1. It specifies the file that contains the Non-Trusted World private key in PEM format. If SAVE_KEYS=1, this file name will be used to save the key.

  • SCP_BL2_KEY: This option is used when GENERATE_COT=1. It specifies the file that contains the SCP_BL2 private key in PEM format. If SAVE_KEYS=1, this file name will be used to save the key.

  • BL31_KEY: This option is used when GENERATE_COT=1. It specifies the file that contains the BL31 private key in PEM format. If SAVE_KEYS=1, this file name will be used to save the key.

  • BL32_KEY: This option is used when GENERATE_COT=1. It specifies the file that contains the BL32 private key in PEM format. If SAVE_KEYS=1, this file name will be used to save the key.

  • BL33_KEY: This option is used when GENERATE_COT=1. It specifies the file that contains the BL33 private key in PEM format. If SAVE_KEYS=1, this file name will be used to save the key.

  • PROGRAMMABLE_RESET_ADDRESS: This option indicates whether the reset vector address can be programmed or is fixed on the platform. It can take either 0 (fixed) or 1 (programmable). Default is 0. If the platform has a programmable reset address, it is expected that a CPU will start executing code directly at the right address, both on a cold and warm reset. In this case, there is no need to identify the entrypoint on boot and the boot path can be optimised. The plat_get_my_entrypoint() platform porting interface does not need to be implemented in this case.

  • COLD_BOOT_SINGLE_CPU: This option indicates whether the platform may release several CPUs out of reset. It can take either 0 (several CPUs may be brought up) or 1 (only one CPU will ever be brought up during cold reset). Default is 0. If the platform always brings up a single CPU, there is no need to distinguish between primary and secondary CPUs and the boot path can be optimised. The plat_is_my_cpu_primary() and plat_secondary_cold_boot_setup() platform porting interfaces do not need to be implemented in this case.

  • PSCI_EXTENDED_STATE_ID: As per PSCI1.0 Specification, there are 2 formats possible for the PSCI power-state parameter viz original and extended State-ID formats. This flag if set to 1, configures the generic PSCI layer to use the extended format. The default value of this flag is 0, which means by default the original power-state format is used by the PSCI implementation. This flag should be specified by the platform makefile and it governs the return value of PSCI_FEATURES API for CPU_SUSPEND smc function id.

  • ERROR_DEPRECATED: This option decides whether to treat the usage of deprecated platform APIs, helper functions or drivers within Trusted Firmware as error. It can take the value 1 (flag the use of deprecated APIs as error) or 0. The default is 0.

  • SPIN_ON_BL1_EXIT: This option introduces an infinite loop in BL1. It can take either 0 (no loop) or 1 (add a loop). 0 is the default. This loop stops execution in BL1 just before handing over to BL31. At this point, all firmware images have been loaded in memory, and the MMU and caches are turned off. Refer to the "Debugging options" section for more details.

  • EL3_PAYLOAD_BASE: This option enables booting an EL3 payload instead of the normal boot flow. It must specify the entry point address of the EL3 payload. Please refer to the "Booting an EL3 payload" section for more details.

  • PL011_GENERIC_UART: Boolean option to indicate the PL011 driver that the underlying hardware is not a full PL011 UART but a minimally compliant generic UART, which is a subset of the PL011. The driver will not access any register that is not part of the SBSA generic UART specification. Default value is 0 (a full PL011 compliant UART is present).

ARM development platform specific build options

  • ARM_TSP_RAM_LOCATION: location of the TSP binary. Options:
    • tsram : Trusted SRAM (default option)
    • tdram : Trusted DRAM (if available)
    • dram : Secure region in DRAM (configured by the TrustZone controller)

For a better understanding of these options, the ARM development platform memory map is explained in the Firmware Design.

  • ARM_ROTPK_LOCATION: used when TRUSTED_BOARD_BOOT=1. It specifies the location of the ROTPK hash returned by the function plat_get_rotpk_info() for ARM platforms. Depending on the selected option, the proper private key must be specified using the ROT_KEY option when building the Trusted Firmware. This private key will be used by the certificate generation tool to sign the BL2 and Trusted Key certificates. Available options for ARM_ROTPK_LOCATION are:

    • regs : return the ROTPK hash stored in the Trusted root-key storage registers. The private key corresponding to this ROTPK hash is not currently available.
    • devel_rsa : return a development public key hash embedded in the BL1 and BL2 binaries. This hash has been obtained from the RSA public key arm_rotpk_rsa.der, located in plat/arm/board/common/rotpk. To use this option, arm_rotprivk_rsa.pem must be specified as ROT_KEY when creating the certificates.

  • ARM_RECOM_STATE_ID_ENC: The PSCI1.0 specification recommends an encoding for the construction of composite state-ID in the power-state parameter. The existing PSCI clients currently do not support this encoding of State-ID yet. Hence this flag is used to configure whether to use the recommended State-ID encoding or not. The default value of this flag is 0, in which case the platform is configured to expect NULL in the State-ID field of power-state parameter.

  • ARM_DISABLE_TRUSTED_WDOG: boolean option to disable the Trusted Watchdog. By default, ARM platforms use a watchdog to trigger a system reset in case an error is encountered during the boot process (for example, when an image could not be loaded or authenticated). The watchdog is enabled in the early platform setup hook at BL1 and disabled in the BL1 prepare exit hook. The Trusted Watchdog may be disabled at build time for testing or development purposes.

  • ARM_CONFIG_CNTACR: boolean option to unlock access to the CNTBase frame registers by setting the CNTCTLBase.CNTACR register bits. The frame number is defined by 'PLAT_ARM_NSTIMER_FRAME_ID', which should match the frame used by the Non-Secure image (normally the Linux kernel). Default is true (access to the frame is allowed).

ARM CSS platform specific build options

  • CSS_DETECT_PRE_1_7_0_SCP: Boolean flag to detect SCP version incompatibility. Version 1.7.0 of the SCP firmware made a non-backwards compatible change to the MTL protocol, used for AP/SCP communication. Trusted Firmware no longer supports earlier SCP versions. If this option is set to 1 then Trusted Firmware will detect if an earlier version is in use. Default is 1.

ARM FVP platform specific build options

  • FVP_USE_GIC_DRIVER : Selects the GIC driver to be built. Options:

    • FVP_GICV2 : The GICv2 only driver is selected
    • FVP_GICV3 : The GICv3 only driver is selected (default option)
    • FVP_GICV3_LEGACY: The Legacy GICv3 driver is selected (deprecated).

    Note that if the FVP is configured for legacy VE memory map, then ARM Trusted Firmware must be compiled with GICv2 only driver using FVP_USE_GIC_DRIVER=FVP_GICV2 build option.

Creating a Firmware Image Package

FIPs are automatically created as part of the build instructions described in the previous section. It is also possible to independently build the FIP creation tool and FIPs if required. To do this, follow these steps:

Build the tool:

make -C tools/fip_create

It is recommended to remove the build artifacts before rebuilding:

make -C tools/fip_create clean

Create a Firmware package that contains existing BL2 and BL31 images:

# fip_create --help to print usage information
# fip_create <fip_name> <images to add> [--dump to show result]
./tools/fip_create/fip_create fip.bin --dump \
   --tb-fw build/<platform>/debug/bl2.bin --soc-fw build/<platform>/debug/bl31.bin

 Firmware Image Package ToC:
---------------------------
- Trusted Boot Firmware BL2: offset=0x88, size=0x81E8
  file: 'build/<platform>/debug/bl2.bin'
- EL3 Runtime Firmware BL31: offset=0x8270, size=0xC218
  file: 'build/<platform>/debug/bl31.bin'
---------------------------
Creating "fip.bin"

View the contents of an existing Firmware package:

./tools/fip_create/fip_create fip.bin --dump

 Firmware Image Package ToC:
---------------------------
- Trusted Boot Firmware BL2: offset=0x88, size=0x81E8
- EL3 Runtime Firmware BL31: offset=0x8270, size=0xC218
---------------------------

Existing package entries can be individually updated:

# Change the BL2 from Debug to Release version
./tools/fip_create/fip_create fip.bin --dump \
  --tb-fw build/<platform>/release/bl2.bin

Firmware Image Package ToC:
---------------------------
- Trusted Boot Firmware BL2: offset=0x88, size=0x7240
  file: 'build/<platform>/release/bl2.bin'
- EL3 Runtime Firmware BL31: offset=0x72C8, size=0xC218
---------------------------
Updating "fip.bin"

Debugging options

To compile a debug version and make the build more verbose use

CROSS_COMPILE=<path-to-aarch64-gcc>/bin/aarch64-linux-gnu- \
BL33=<path-to>/<bl33_image>                                \
make PLAT=<platform> DEBUG=1 V=1 all fip

AArch64 GCC uses DWARF version 4 debugging symbols by default. Some tools (for example DS-5) might not support this and may need an older version of DWARF symbols to be emitted by GCC. This can be achieved by using the -gdwarf-<version> flag, with the version being set to 2 or 3. Setting the version to 2 is recommended for DS-5 versions older than 5.16.

When debugging logic problems it might also be useful to disable all compiler optimizations by using -O0.

NOTE: Using -O0 could cause output images to be larger and base addresses might need to be recalculated (see the Memory layout on ARM development platforms section in the Firmware Design).

Extra debug options can be passed to the build system by setting CFLAGS:

CFLAGS='-O0 -gdwarf-2'                                     \
CROSS_COMPILE=<path-to-aarch64-gcc>/bin/aarch64-linux-gnu- \
BL33=<path-to>/<bl33_image>                                \
make PLAT=<platform> DEBUG=1 V=1 all fip

It is also possible to introduce an infinite loop to help in debugging the post-BL2 phase of the Trusted Firmware. This can be done by rebuilding BL1 with the SPIN_ON_BL1_EXIT=1 build flag. Refer to the "Summary of build options" section. In this case, the developer may take control of the target using a debugger when indicated by the console output. When using DS-5, the following commands can be used:

# Stop target execution
interrupt

#
# Prepare your debugging environment, e.g. set breakpoints
#

# Jump over the debug loop
set var $AARCH64::$Core::$PC = $AARCH64::$Core::$PC + 4

# Resume execution
continue

Building the Test Secure Payload

The TSP is coupled with a companion runtime service in the BL31 firmware, called the TSPD. Therefore, if you intend to use the TSP, the BL31 image must be recompiled as well. For more information on SPs and SPDs, see the "Secure-EL1 Payloads and Dispatchers" section in the Firmware Design.

First clean the Trusted Firmware build directory to get rid of any previous BL31 binary. Then to build the TSP image and include it into the FIP use:

CROSS_COMPILE=<path-to-aarch64-gcc>/bin/aarch64-linux-gnu- \
BL33=<path-to>/<bl33_image>                                \
make PLAT=<platform> SPD=tspd all fip

An additional boot loader binary file is created in the build directory:

  • build/<platform>/<build-type>/bl32.bin

The FIP will now contain the additional BL32 image. Here is an example output from an FVP build in release mode including BL32 and using FVP_AARCH64_EFI.fd as BL33 image:

Firmware Image Package ToC:
---------------------------
- Trusted Boot Firmware BL2: offset=0xD8, size=0x6000
  file: './build/fvp/release/bl2.bin'
- EL3 Runtime Firmware BL31: offset=0x60D8, size=0x9000
  file: './build/fvp/release/bl31.bin'
- Secure Payload BL32 (Trusted OS): offset=0xF0D8, size=0x3000
  file: './build/fvp/release/bl32.bin'
- Non-Trusted Firmware BL33: offset=0x120D8, size=0x280000
  file: '../FVP_AARCH64_EFI.fd'
---------------------------
Creating "build/fvp/release/fip.bin"

Building the Certificate Generation Tool

The cert_create tool can be built separately through the following commands:

$ cd tools/cert_create
$ make PLAT=<platform> [DEBUG=1] [V=1]

DEBUG=1 builds the tool in debug mode. V=1 makes the build process more verbose. The following command should be used to obtain help about the tool:

$ ./cert_create -h

The cert_create tool is automatically built with the fip target when GENERATE_COT=1.

Building FIP images with support for Trusted Board Boot

Trusted Board Boot primarily consists of the following two features:

The following steps should be followed to build FIP and (optionally) FWU_FIP images with support for these features:

  1. Fulfill the dependencies of the mbedtls cryptographic and image parser modules by checking out a recent version of the mbed TLS Repository. It is important to use a version that is compatible with TF and fixes any known security vulnerabilities. See mbed TLS Security Center for more information. This version of TF is tested with tag mbedtls-2.2.0.

    The drivers/auth/mbedtls/mbedtls_*.mk files contain the list of mbed TLS source files the modules depend upon. include/drivers/auth/mbedtls/mbedtls_config.h contains the configuration options required to build the mbed TLS sources.

    Note that the mbed TLS library is licensed under the Apache version 2.0 license. Using mbed TLS source code will affect the licensing of Trusted Firmware binaries that are built using this library.

  2. To build the FIP image, ensure the following command line variables are set while invoking make to build Trusted Firmware:

    • MBEDTLS_DIR=<path of the directory containing mbed TLS sources>
    • TRUSTED_BOARD_BOOT=1
    • GENERATE_COT=1

    In the case of ARM platforms, the location of the ROTPK hash must also be specified at build time. Two locations are currently supported (see ARM_ROTPK_LOCATION build option):

    • ARM_ROTPK_LOCATION=regs: the ROTPK hash is obtained from the Trusted root-key storage registers present in the platform. On Juno, this registers are read-only. On FVP Base and Cortex models, the registers are read-only, but the value can be specified using the command line option bp.trusted_key_storage.public_key when launching the model. On both Juno and FVP models, the default value corresponds to an ECDSA-SECP256R1 public key hash, whose private part is not currently available.

    • ARM_ROTPK_LOCATION=devel_rsa: use the ROTPK hash that is hardcoded in the ARM platform port. The private/public RSA key pair may be found in plat/arm/board/common/rotpk.

    Example of command line using RSA development keys:

    CROSS_COMPILE=<path-to-aarch64-gcc>/bin/aarch64-linux-gnu-      \
BL33=<path-to>/<bl33_image>                                     \
MBEDTLS_DIR=<path of the directory containing mbed TLS sources> \
make PLAT=<platform> TRUSTED_BOARD_BOOT=1 GENERATE_COT=1        \
ARM_ROTPK_LOCATION=devel_rsa                                    \
ROT_KEY=plat/arm/board/common/rotpk/arm_rotprivk_rsa.pem        \
all fip

    The result of this build will be the bl1.bin and the fip.bin binaries, with the difference that the FIP will include the certificates corresponding to the Chain of Trust described in the TBBR-client document. These certificates can also be found in the output build directory.

  3. The optional FWU_FIP contains any additional images to be loaded from Non-Volatile storage during the Firmware Update process. To build the FWU_FIP, any FWU images required by the platform must be specified on the command line. On ARM development platforms like Juno, these are:

    • NS_BL2U. The AP non-secure Firmware Updater image.
    • SCP_BL2U. The SCP Firmware Update Configuration image.

    Example of Juno command line for generating both fwu and fwu_fip targets using RSA development:

    CROSS_COMPILE=<path-to-aarch64-gcc>/bin/aarch64-none-elf-       \
BL33=<path-to>/<bl33_image>                                     \
SCP_BL2=<path-to>/<scp_bl2_image>                               \
SCP_BL2U=<path-to>/<scp_bl2u_image>                             \
NS_BL2U=<path-to>/<ns_bl2u_image>                               \
MBEDTLS_DIR=<path of the directory containing mbed TLS sources> \
make PLAT=juno TRUSTED_BOARD_BOOT=1 GENERATE_COT=1              \
ARM_ROTPK_LOCATION=devel_rsa                                    \
ROT_KEY=plat/arm/board/common/rotpk/arm_rotprivk_rsa.pem        \
all fip fwu_fip

    Note: The BL2U image will be built by default and added to the FWU_FIP. The user may override this by adding BL2U=<path-to>/<bl2u_image> to the command line above.

    Note: Building and installing the non-secure and SCP FWU images (NS_BL1U, NS_BL2U and SCP_BL2U) is outside the scope of this document.

    The result of this build will be bl1.bin, fip.bin and fwu_fip.bin binaries. Both the FIP and FWU_FIP will include the certificates corresponding to the Chain of Trust described in the TBBR-client document. These certificates can also be found in the output build directory.

Checking source code style

When making changes to the source for submission to the project, the source must be in compliance with the Linux style guide, and to assist with this check the project Makefile contains two targets, which both utilise the checkpatch.pl script that ships with the Linux source tree.

To check the entire source tree, you must first download a copy of checkpatch.pl (or the full Linux source), set the CHECKPATCH environment variable to point to the script and build the target checkcodebase:

make CHECKPATCH=<path-to-linux>/linux/scripts/checkpatch.pl checkcodebase

To just check the style on the files that differ between your local branch and the remote master, use:

make CHECKPATCH=<path-to-linux>/linux/scripts/checkpatch.pl checkpatch

If you wish to check your patch against something other than the remote master, set the BASE_COMMIT variable to your desired branch. By default, BASE_COMMIT is set to origin/master.

  1. Building the rest of the software stack

The Linaro release provides a set of scripts that automate the process of building all components of the software stack. However, the scripts only support a limited number of Trusted Firmware build options. Therefore, it is recommended to modify these scripts to build all components except Trusted Firmware, and build Trusted Firmware separately as described in the section "Building the Trusted Firmware" above.

The instructions below are targeted at an OpenEmbedded filesystem.

  1. To exclude Trusted Firmware from the automated build process, edit the variant file build-scripts/variants/<platform>-oe, where <platform> is either fvp or juno. Add the following lines at the end of the file:

    # Disable ARM Trusted Firmware build
ARM_TF_BUILD_ENABLED=0

  2. Launch the build script:

    CROSS_COMPILE=aarch64-linux-gnu- \
build-scripts/build-all.sh <platform>-oe

Preparing the Firmware Image Package

The EDK2 binary should be specified as BL33 in the make command line when building the Trusted Firmware. See the "Building the Trusted Firmware" section above. The EDK2 binary for use with the ARM Trusted Firmware can be found here:

uefi/edk2/Build/ArmVExpress-FVP-AArch64-Minimal/DEBUG_GCC49/FV/FVP_AARCH64_EFI.fd   [for FVP]
uefi/edk2/Build/ArmJuno/DEBUG_GCC49/FV/BL33_AP_UEFI.fd                              [for Juno]

Building an alternative EDK2

  • By default, EDK2 is built in debug mode. To build a release version instead, change the following line in the variant file:

    UEFI_BUILD_MODE=DEBUG

    into:

    UEFI_BUILD_MODE=RELEASE

  • On FVP, if legacy GICv2 locations are used, the EDK2 platform makefile must be updated. This is required as EDK2 does not support probing for the GIC location. To do this, first clean the EDK2 build directory:

    build-scripts/build-uefi.sh fvp-oe clean

    Then edit the following file:

    uefi/edk2/ArmPlatformPkg/ArmVExpressPkg/ArmVExpress-FVP-AArch64.mak

    and add the following build flag into the EDK2_MACROS variable:

    -D ARM_FVP_LEGACY_GICV2_LOCATION=1

    Then rebuild everything as described above in step 2.

    Finally rebuild the Trusted Firmware to generate a new FIP using the instructions in the "Building the Trusted Firmware" section.

  1. EL3 payloads alternative boot flow

On a pre-production system, the ability to execute arbitrary, bare-metal code at the highest exception level is required. It allows full, direct access to the hardware, for example to run silicon soak tests.

Although it is possible to implement some baremetal secure firmware from scratch, this is a complex task on some platforms, depending on the level of configuration required to put the system in the expected state.

Rather than booting a baremetal application, a possible compromise is to boot EL3 payloads through the Trusted Firmware instead. This is implemented as an alternative boot flow, where a modified BL2 boots an EL3 payload, instead of loading the other BL images and passing control to BL31. It reduces the complexity of developing EL3 baremetal code by:

  • putting the system into a known architectural state;
  • taking care of platform secure world initialization;
  • loading the SCP_BL2 image if required by the platform.

When booting an EL3 payload on ARM standard platforms, the configuration of the TrustZone controller is simplified such that only region 0 is enabled and is configured to permit secure access only. This gives full access to the whole DRAM to the EL3 payload.

The system is left in the same state as when entering BL31 in the default boot flow. In particular:

  • Running in EL3;
  • Current state is AArch64;
  • Little-endian data access;
  • All exceptions disabled;
  • MMU disabled;
  • Caches disabled.
  1. Preparing the images to run on FVP

Note: This section can be ignored when booting an EL3 payload, as no Flattened Device Tree or kernel image is needed in this case.

Obtaining the Flattened Device Trees

Depending on the FVP configuration and Linux configuration used, different FDT files are required. FDTs for the Foundation and Base FVPs can be found in the Trusted Firmware source directory under fdts/. The Foundation FVP has a subset of the Base FVP components. For example, the Foundation FVP lacks CLCD and MMC support, and has only one CPU cluster.

Note: It is not recommended to use the FDTs built along the kernel because not all FDTs are available from there.

  • fvp-base-gicv2-psci.dtb

    (Default) For use with both AEMv8 and Cortex-A57-A53 Base FVPs with Base memory map configuration.

  • fvp-base-gicv2legacy-psci.dtb

    For use with AEMv8 Base FVP with legacy VE GIC memory map configuration.

  • fvp-base-gicv3-psci.dtb

    For use with both AEMv8 and Cortex-A57-A53 Base FVPs with Base memory map configuration and Linux GICv3 support.

  • fvp-foundation-gicv2-psci.dtb

    (Default) For use with Foundation FVP with Base memory map configuration.

  • fvp-foundation-gicv2legacy-psci.dtb

    For use with Foundation FVP with legacy VE GIC memory map configuration.

  • fvp-foundation-gicv3-psci.dtb

    For use with Foundation FVP with Base memory map configuration and Linux GICv3 support.

Copy the chosen FDT blob as fdt.dtb to the directory from which the FVP is launched. Alternatively a symbolic link may be used.

Preparing the kernel image

Copy the kernel image file linux/arch/arm64/boot/Image to the directory from which the FVP is launched. Alternatively a symbolic link may be used.

  1. Running the software on FVP

This version of the ARM Trusted Firmware has been tested on the following ARM FVPs (64-bit versions only).

  • Foundation_Platform (Version 9.4, Build 9.4.59)
  • FVP_Base_AEMv8A-AEMv8A (Version 7.0, Build 0.8.7004)
  • FVP_Base_Cortex-A57x4-A53x4 (Version 7.0, Build 0.8.7004)
  • FVP_Base_Cortex-A57x1-A53x1 (Version 7.0, Build 0.8.7004)
  • FVP_Base_Cortex-A57x2-A53x4 (Version 7.0, Build 0.8.7004)

NOTE: The build numbers quoted above are those reported by launching the FVP with the --version parameter.

NOTE: The software will not work on Version 1.0 of the Foundation FVP. The commands below would report an unhandled argument error in this case.

NOTE: The Foundation FVP does not provide a debugger interface.

The Foundation FVP is a cut down version of the AArch64 Base FVP. It can be downloaded for free from ARM's website.

The Linaro release provides a script to run the software on FVP. However, it only supports a limited number of model parameter options. Therefore, it is recommended to launch the FVP manually for all use cases described below.

Please refer to the FVP documentation for a detailed description of the model parameter options. A brief description of the important ones that affect the ARM Trusted Firmware and normal world software behavior is provided below.

Running on the Foundation FVP with reset to BL1 entrypoint

The following Foundation_Platform parameters should be used to boot Linux with 4 CPUs using the ARM Trusted Firmware.

<path-to>/Foundation_Platform                   \
--cores=4                                       \
--secure-memory                                 \
--visualization                                 \
--gicv3                                         \
--data="<path-to>/<bl1-binary>"@0x0             \
--data="<path-to>/<FIP-binary>"@0x08000000      \
--data="<path-to>/<fdt>"@0x83000000             \
--data="<path-to>/<kernel-binary>"@0x80080000   \
--block-device="<path-to>/<file-system-image>"

  1. The --data="<path-to-some-binary>"@0x... parameters are used to load binaries into memory.

    • BL1 is loaded at the start of the Trusted ROM.
    • The Firmware Image Package is loaded at the start of NOR FLASH0.
    • The Linux kernel image and device tree are loaded in DRAM.

  2. The --block-device parameter is used to specify the path to the file system image provided to Linux via VirtioBlock. Note that it must point to the real file and that a symbolic link to this file cannot be used with the FVP.

The default use-case for the Foundation FVP is to enable the GICv3 device in the model but use the GICv2 FDT, in order for Linux to drive the GIC in GICv2 emulation mode.

Notes regarding Base FVP configuration options

Please refer to these notes in the subsequent "Running on the Base FVP" sections.

  1. The -C bp.flashloader0.fname parameter is used to load a Firmware Image Package at the start of NOR FLASH0 (see the "Building the Trusted Firmware" section above).

  2. Using cache_state_modelled=1 makes booting very slow. The software will still work (and run much faster) without this option but this will hide any cache maintenance defects in the software.

  3. The -C bp.virtioblockdevice.image_path parameter is used to specify the path to the file system image provided to Linux via VirtioBlock. Note that it must point to the real file and that a symbolic link to this file cannot be used with the FVP. Ensure that the FVP doesn't output any error messages. If the following error message is displayed:

    ERROR: BlockDevice: Failed to open "<path-to>/<file-system-image>"!

    then make sure the path to the file-system image in the model parameter is correct and that read permission is correctly set on the file-system image file.

  4. Setting the -C bp.secure_memory parameter to 1 is only supported on Base FVP versions 5.4 and newer. Setting this parameter to 0 is also supported. The -C bp.tzc_400.diagnostics=1 parameter is optional. It instructs the FVP to provide some helpful information if a secure memory violation occurs.

  5. The --data="<path-to-some-binary>"@<base-address-of-binary> parameter is used to load images into Base FVP memory. The base addresses used should match the image base addresses used while linking the images. This parameter is used to load the Linux kernel image and device tree into DRAM.

  6. This and the following notes only apply when the firmware is built with the RESET_TO_BL31 option.

    The --data="<path-to><bl31|bl32|bl33-binary>"@<base-address-of-binary> parameter is needed to load the individual bootloader images in memory. BL32 image is only needed if BL31 has been built to expect a Secure-EL1 Payload.

  7. The -C cluster<X>.cpu<Y>.RVBAR=@<base-address-of-bl31> parameter, where X and Y are the cluster and CPU numbers respectively, is used to set the reset vector for each core.

  8. Changing the default value of ARM_TSP_RAM_LOCATION will also require changing the value of --data="<path-to><bl32-binary>"@<base-address-of-bl32> to the new value of BL32_BASE.

Running on the AEMv8 Base FVP with reset to BL1 entrypoint

Please read "Notes regarding Base FVP configuration options" section above for information about some of the options to run the software.

The following FVP_Base_AEMv8A-AEMv8A parameters should be used to boot Linux with 8 CPUs using the ARM Trusted Firmware.

<path-to>/FVP_Base_AEMv8A-AEMv8A                            \
-C pctl.startup=0.0.0.0                                     \
-C bp.secure_memory=1                                       \
-C bp.tzc_400.diagnostics=1                                 \
-C cluster0.NUM_CORES=4                                     \
-C cluster1.NUM_CORES=4                                     \
-C cache_state_modelled=1                                   \
-C bp.secureflashloader.fname="<path-to>/<bl1-binary>"      \
-C bp.flashloader0.fname="<path-to>/<FIP-binary>"           \
--data cluster0.cpu0="<path-to>/<fdt>"@0x83000000           \
--data cluster0.cpu0="<path-to>/<kernel-binary>"@0x80080000 \
-C bp.virtioblockdevice.image_path="<path-to>/<file-system-image>"

Running on the Cortex-A57-A53 Base FVP with reset to BL1 entrypoint

Please read "Notes regarding Base FVP configuration options" section above for information about some of the options to run the software.

The following FVP_Base_Cortex-A57x4-A53x4 model parameters should be used to boot Linux with 8 CPUs using the ARM Trusted Firmware.

<path-to>/FVP_Base_Cortex-A57x4-A53x4                       \
-C pctl.startup=0.0.0.0                                     \
-C bp.secure_memory=1                                       \
-C bp.tzc_400.diagnostics=1                                 \
-C cache_state_modelled=1                                   \
-C bp.secureflashloader.fname="<path-to>/<bl1-binary>"      \
-C bp.flashloader0.fname="<path-to>/<FIP-binary>"           \
--data cluster0.cpu0="<path-to>/<fdt>"@0x83000000           \
--data cluster0.cpu0="<path-to>/<kernel-binary>"@0x80080000 \
-C bp.virtioblockdevice.image_path="<path-to>/<file-system-image>"

Running on the AEMv8 Base FVP with reset to BL31 entrypoint

Please read "Notes regarding Base FVP configuration options" section above for information about some of the options to run the software.

The following FVP_Base_AEMv8A-AEMv8A parameters should be used to boot Linux with 8 CPUs using the ARM Trusted Firmware.

<path-to>/FVP_Base_AEMv8A-AEMv8A                             \
-C pctl.startup=0.0.0.0                                      \
-C bp.secure_memory=1                                        \
-C bp.tzc_400.diagnostics=1                                  \
-C cluster0.NUM_CORES=4                                      \
-C cluster1.NUM_CORES=4                                      \
-C cache_state_modelled=1                                    \
-C cluster0.cpu0.RVBAR=0x04023000                            \
-C cluster0.cpu1.RVBAR=0x04023000                            \
-C cluster0.cpu2.RVBAR=0x04023000                            \
-C cluster0.cpu3.RVBAR=0x04023000                            \
-C cluster1.cpu0.RVBAR=0x04023000                            \
-C cluster1.cpu1.RVBAR=0x04023000                            \
-C cluster1.cpu2.RVBAR=0x04023000                            \
-C cluster1.cpu3.RVBAR=0x04023000                            \
--data cluster0.cpu0="<path-to>/<bl31-binary>"@0x04023000    \
--data cluster0.cpu0="<path-to>/<bl32-binary>"@0x04001000    \
--data cluster0.cpu0="<path-to>/<bl33-binary>"@0x88000000    \
--data cluster0.cpu0="<path-to>/<fdt>"@0x83000000            \
--data cluster0.cpu0="<path-to>/<kernel-binary>"@0x80080000  \
-C bp.virtioblockdevice.image_path="<path-to>/<file-system-image>"

Running on the Cortex-A57-A53 Base FVP with reset to BL31 entrypoint

Please read "Notes regarding Base FVP configuration options" section above for information about some of the options to run the software.

The following FVP_Base_Cortex-A57x4-A53x4 model parameters should be used to boot Linux with 8 CPUs using the ARM Trusted Firmware.

<path-to>/FVP_Base_Cortex-A57x4-A53x4                        \
-C pctl.startup=0.0.0.0                                      \
-C bp.secure_memory=1                                        \
-C bp.tzc_400.diagnostics=1                                  \
-C cache_state_modelled=1                                    \
-C cluster0.cpu0.RVBARADDR=0x04023000                        \
-C cluster0.cpu1.RVBARADDR=0x04023000                        \
-C cluster0.cpu2.RVBARADDR=0x04023000                        \
-C cluster0.cpu3.RVBARADDR=0x04023000                        \
-C cluster1.cpu0.RVBARADDR=0x04023000                        \
-C cluster1.cpu1.RVBARADDR=0x04023000                        \
-C cluster1.cpu2.RVBARADDR=0x04023000                        \
-C cluster1.cpu3.RVBARADDR=0x04023000                        \
--data cluster0.cpu0="<path-to>/<bl31-binary>"@0x04023000    \
--data cluster0.cpu0="<path-to>/<bl32-binary>"@0x04001000    \
--data cluster0.cpu0="<path-to>/<bl33-binary>"@0x88000000    \
--data cluster0.cpu0="<path-to>/<fdt>"@0x83000000            \
--data cluster0.cpu0="<path-to>/<kernel-binary>"@0x80080000  \
-C bp.virtioblockdevice.image_path="<path-to>/<file-system-image>"

Configuring the GICv2 memory map

The Base FVP models support GICv2 with the default model parameters at the following addresses. The Foundation FVP also supports these addresses when configured for GICv3 in GICv2 emulation mode.

GICv2 Distributor Interface     0x2f000000
GICv2 CPU Interface             0x2c000000
GICv2 Virtual CPU Interface     0x2c010000
GICv2 Hypervisor Interface      0x2c02f000

The AEMv8 Base FVP can be configured to support GICv2 at addresses corresponding to the legacy (Versatile Express) memory map as follows. These are the default addresses when using the Foundation FVP in GICv2 mode.

GICv2 Distributor Interface     0x2c001000
GICv2 CPU Interface             0x2c002000
GICv2 Virtual CPU Interface     0x2c004000
GICv2 Hypervisor Interface      0x2c006000

The choice of memory map is reflected in the build variant field (bits[15:12]) in the SYS_ID register (Offset 0x0) in the Versatile Express System registers memory map (0x1c010000).

  • SYS_ID.Build[15:12]

    0x1 corresponds to the presence of the Base GIC memory map. This is the default value on the Base FVPs.

  • SYS_ID.Build[15:12]

    0x0 corresponds to the presence of the Legacy VE GIC memory map. This is the default value on the Foundation FVP.

This register can be configured as described in the following sections.

NOTE: If the legacy VE GIC memory map is used, then Trusted Firmware must be compiled with the GICv2 only driver, and the corresponding FDT and BL33 images should be used.

Configuring AEMv8 Foundation FVP GIC for legacy VE memory map

The following parameters configure the Foundation FVP to use GICv2 with the legacy VE memory map:

<path-to>/Foundation_Platform             \
--cores=4                                 \
--secure-memory                           \
--visualization                           \
--no-gicv3                                \
--data="<path-to>/<bl1-binary>"@0x0       \
--data="<path-to>/<FIP-binary>"@0x8000000 \
--block-device="<path-to>/<file-system-image>"

Explicit configuration of the SYS_ID register is not required.

Configuring AEMv8 Base FVP GIC for legacy VE memory map

The following parameters configure the AEMv8 Base FVP to use GICv2 with the legacy VE memory map. They must added to the parameters described in the "Running on the AEMv8 Base FVP" section above:

-C cluster0.gic.GICD-offset=0x1000                  \
-C cluster0.gic.GICC-offset=0x2000                  \
-C cluster0.gic.GICH-offset=0x4000                  \
-C cluster0.gic.GICH-other-CPU-offset=0x5000        \
-C cluster0.gic.GICV-offset=0x6000                  \
-C cluster0.gic.PERIPH-size=0x8000                  \
-C cluster1.gic.GICD-offset=0x1000                  \
-C cluster1.gic.GICC-offset=0x2000                  \
-C cluster1.gic.GICH-offset=0x4000                  \
-C cluster1.gic.GICH-other-CPU-offset=0x5000        \
-C cluster1.gic.GICV-offset=0x6000                  \
-C cluster1.gic.PERIPH-size=0x8000                  \
-C gic_distributor.GICD-alias=0x2c001000            \
-C gicv3.gicv2-only=1                               \
-C bp.variant=0x0

The bp.variant parameter corresponds to the build variant field of the SYS_ID register. Setting this to 0x0 allows the ARM Trusted Firmware to detect the legacy VE memory map while configuring the GIC.

Booting an EL3 payload on FVP

Booting an EL3 payload on FVP requires a couple of changes to the way the model is normally invoked.

First of all, the EL3 payload image is not part of the FIP and is not loaded by the Trusted Firmware. Therefore, it must be loaded in memory some other way. There are 2 ways of doing that:

  1. It can be loaded over JTAG at the appropriate time. The infinite loop introduced in BL1 when compiling the Trusted Firmware with SPIN_ON_BL1_EXIT=1 stops execution at the right moment for a debugger to take control of the target and load the payload.

  2. It can be pre-loaded in the FVP memory using the following model parameter:

    --data="<path-to-binary>"@<base-address-of-binary>

    The base address provided to the FVP must match the EL3_PAYLOAD_BASE address used when building the Trusted Firmware.

Secondly, the EL3 payloads boot flow requires the CPUs mailbox to be cleared at reset for the secondary CPUs holding pen to work properly. Unfortunately, its reset value is undefined on FVP. One way to clear it is to create an 8-byte file containing all zero bytes and pre-load it into the FVP memory at the mailbox address (i.e. 0x04000000) using the same --data FVP parameter as described above.

The following command creates such a file called mailbox.dat:

dd if=/dev/zero of=mailbox.dat bs=1 count=8
  1. Running the software on Juno

This version of the ARM Trusted Firmware has been tested on Juno r0 and Juno r1.

To execute the software stack on Juno, the version of the Juno board recovery image indicated in the Linaro Release Notes must be installed. If you have an earlier version installed or are unsure which version is installed, please re-install the recovery image by following the Instructions for using Linaro's deliverables on Juno.

Preparing Trusted Firmware images

The Juno platform requires a SCP_BL1 and a SCP_BL2 image to boot up. The SCP_BL1 image contains the ROM firmware that runs on the SCP (System Control Processor), whereas the SCP_BL2 image contains the SCP Runtime firmware. Both images are embedded within the Juno board recovery image, these are the files bl0.bin and bl30.bin, respectively. Please note that these filenames still use the old terminology.

The SCP_BL2 file must be part of the FIP image. Therefore, its path must be supplied using the SCP_BL2 variable on the command line when building the FIP. Please refer to the section "Building the Trusted Firmware".

After building Trusted Firmware, the files bl1.bin and fip.bin need copying to the SOFTWARE/ directory of the Juno SD card.

Other Juno software information

Please visit the ARM Platforms Portal to get support and obtain any other Juno software information. Please also refer to the Juno Getting Started Guide to get more detailed information about the Juno ARM development platform and how to configure it.

Testing SYSTEM SUSPEND on Juno

The SYSTEM SUSPEND is a PSCI API which can be used to implement system suspend to RAM. For more details refer to section 5.16 of PSCI. The Linaro Release Notes point to the required SCP and motherboard firmware binaries supporting this feature on Juno. The mainline linux kernel does not yet have support for this feature on Juno but it is queued to be merged in v4.4. Till that becomes available, the feature can be tested by using a custom kernel built from the following repository:

git clone git://git.kernel.org/pub/scm/linux/kernel/git/lpieralisi/linux.git
cd linux
git checkout firmware/psci-1.0

Configure the linux kernel:

export CROSS_COMPILE=<path-to-aarch64-gcc>/bin/aarch64-linux-gnu-
make ARCH=arm64 defconfig

The feature is tested conveniently by using the RTC. Enable the RTC driver in menuconfig

make ARCH=arm64 menuconfig

The PL031 RTC driver can be enabled at the following location in menuconfig

ARM AMBA PL031 RTC
  |   Location:
  |     -> Device Drivers
  |       -> Real Time Clock

Build the kernel

make ARCH=arm64 Image -j8

Replace the kernel image in the SOFTWARE/ directory of the Juno SD card with the Image from arch/arm64/boot/ of the linux directory.

Reset the board and wait for it to boot. At the shell prompt issue the following command:

echo +10 > /sys/class/rtc/rtc1/wakealarm
echo -n mem > /sys/power/state

The Juno board should suspend to RAM and then wakeup after 10 seconds due to wakeup interrupt from RTC.

  1. Changes required for booting Linux on FVP in GICv3 mode

In case the TF FVP port is built with the build option FVP_USE_GIC_DRIVER=FVP_GICV3, then the GICv3 hardware cannot be used in GICv2 legacy mode. The default build of UEFI for FVP in latest tracking kernel configures GICv3 in GICv2 legacy mode. This can be changed by setting the build flag gArmTokenSpaceGuid.PcdArmGicV3WithV2Legacy to FALSE in uefi/edk2/ArmPlatformPkg/ArmVExpressPkg/ArmVExpress-FVP-AArch64.dsc.

Recompile UEFI as mentioned here.

The GICv3 DTBs found in ARM Trusted Firmware source directory can be used to test the GICv3 kernel on the respective FVP models.

Copyright (c) 2013-2015, ARM Limited and Contributors. All rights reserved.