Re: [Buildroot] [PATCH v2 11/14] board/mender/x86_64: add a udev rule to create /dev/root

[Thomas Petazzoni via buildroot <buildroot@buildroot.org>]

On Tue, Oct 27, 2026 at 05:40:08PM +0100, Adam Duskett wrote:
> As /dev/root does not appear automatically, add a rule to
> create /dev/root. Without this rule, even running a simple command
> outputs the following warning:

Which "simple command"? Are we talking about Mender commands/tools?

> 
> ```
> WARN[0000] Could not resolve path link: /dev/root Attempting to continue
> WARN[0000] Could not resolve path link: /dev/root Attempting to continue
> ```
> 
> Signed-off-by: Adam Duskett <adam.duskett@amarulasolutions.com>
> ---
>  .../mender/x86_64/overlay/etc/udev/rules.d/99-root-symlink.rules | 1 +
>  1 file changed, 1 insertion(+)
>  create mode 100644 board/mender/x86_64/overlay/etc/udev/rules.d/99-root-symlink.rules
> 
> diff --git a/board/mender/x86_64/overlay/etc/udev/rules.d/99-root-symlink.rules b/board/mender/x86_64/overlay/etc/udev/rules.d/99-root-symlink.rules
> new file mode 100644
> index 0000000000..7d2ae8cb89
> --- /dev/null
> +++ b/board/mender/x86_64/overlay/etc/udev/rules.d/99-root-symlink.rules
> @@ -0,0 +1 @@
> +SUBSYSTEM=="block", ACTION=="add|change", PROGRAM="/bin/grep -q root=/dev/%k /proc/cmdline", SYMLINK+="root"

Is this supposed to work in all cases, or just for the "basic" case of
our defconfig?

For example on my machine, /proc/cmdline has
root=UUID=898654ab-a9dc-46ee-922f-8f5077c83176, and I don't think a
symlink /dev/root -> /dev/UUID=898654ab-a9dc-46ee-922f-8f5077c83176
would work well.

Note: I'm fine if the answer is "it works for the basic case of this
defconfig".

Thanks!

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com
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