Skip to content
Daniel Wagner edited this page Oct 17, 2025 · 10 revisions

nvme show-regs /dev/nvme0 returns: nvme0 failed to map

It's more of a "feature" than an issue. The kernel will not allow user space to map a device's IO memory when that config option is set and the tooling can't get around that limitation.

When the Linux kernel is configured with CONFIG_IO_STRICT_DEVMEM, the kernel prevents user space to map IO memory to userspace. Either compile a kernel without this option enabled or set the kernel command line option iomem=relaxed.

Also when secure boot is enabled the lockdown is activated, which prevents mapping PCI bars to user space.

nvme list shows wrong disk/block size

nvme-cli v2 relies on the kernel reporting the correct disk/block size via the sysfs interface.

Also ensure libnvme has:

and Linux kernel has (v6.8):

nvme id-ns shows the correct disk/block size because it will issue a command to read the current value.

nvme list shows old firmware version after firmware udpate

nvme-cli reads the firmware version from sysfs. Older kernel don't update the firmware entry in sysfs after an firmware upgrade. After a reboot the correct version will be shown. Alternatively you can use nvme id-ctrl to check the firmware version.

Linux kernel fix (v6.2)

If this still doesn't fix your problem, it needs to be addressed in the kernel. nvme list is a non privileged operation and thus can't issue any NVMe Commands via the passthru interface. This is on purpose.

The workaround is to use nvme id-ctrl, reset the PCI device or reboot the machine.

Clone this wiki locally