Re: [PATCH] scripts: Add script to extract built-in firmware blobs

[Andrew Morton <akpm@linux-foundation.org>]

On Fri, 24 Jan 2025 09:31:07 -0300 "Guilherme G. Piccoli" <gpiccoli@igalia.com> wrote:

> On 24/01/2025 03:38, Andrew Morton wrote:
> > On Mon, 20 Jan 2025 16:04:26 -0300 "Guilherme G. Piccoli" <gpiccoli@igalia.com> wrote:
> > 
> >> Through the options CONFIG_EXTRA_FIRMWARE{_DIR} one is able to build
> >> a kernel including firmware blobs in a built-in fashion. This is
> >> usually the case of built-in drivers that require some blobs in
> >> order to work properly, for example, like in non-initrd based systems.
> >>
> >> Add hereby a script to extract these blobs from a non-stripped vmlinux,
> >> similar to the idea of "extract-ikconfig". The firmware loader interface
> >> saves such built-in blobs as rodata entries, having a field for the FW
> >> name as "_fw_<module_name>_<firmware_name>_bin"; the tool extracts files
> >> named "<module_name>_<firmware_name>" for each rodata firmware entry
> >> detected. It makes use of awk, bash, dd and readelf, pretty standard
> >> tooling for Linux development.
> > 
> > Please describe the use case(s) for this.  ie, why are you suggesting
> > this be added to Linux?
> > 
> 
> Hi Andrew, there is currently no tool to extract a firmware blob that is
> built-in on vmlinux to the best of my knowledge. So if we have a kernel
> image containing the blobs, and we want to rebuild the kernel with some
> debug patches for example (and given that the image also has
> IKCONFIG=y), we currently can't do that for the same versions for all
> the firmware blobs, _unless_ we have exact commits of linux-firmware for
> the specific versions for each firmware included.
> 
> With this tool, we can blindly extract the FWs and easily re-add them in
> the new debug kernel build, allowing a more deterministic testing
> without the burden of "hunting down" the proper version of each firmware
> binary.
> 
> Makes sense to you?

OK, thanks.  I (badly) pasted the above into the changelog.