[Buildroot] [PATCH-NEXT 4/4] linux: build after linux-firmware if enabled for early loading support

[Yann E. MORIN]

On 2021-02-12 19:40 +0100, Peter Korsgaard spake thusly:
> To support building in (a subset of) the linux-firmware files into the
> kernel using the CONFIG_EXTRA_FIRMWARE option, we need to ensure that the
> firmware files are installed before the Linux kernel is built, similar to
> how it is done for intel-microcode.
> 
> Signed-off-by: Peter Korsgaard <peter at korsgaard.com>
> ---
>  linux/linux.mk | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/linux/linux.mk b/linux/linux.mk
> index a212f42c28..5e4b319cf1 100644
> --- a/linux/linux.mk
> +++ b/linux/linux.mk
> @@ -78,7 +78,8 @@ LINUX_MAKE_ENV = \
>  
>  LINUX_INSTALL_IMAGES = YES
>  LINUX_DEPENDENCIES = host-kmod \
> -	$(if $(BR2_PACKAGE_INTEL_MICROCODE),intel-microcode)
> +	$(if $(BR2_PACKAGE_INTEL_MICROCODE),intel-microcode) \
> +	$(if $(BR2_PACKAGE_LINUX_FIRMWARE),linux-firmware)

You also need to tell the kernel where to find those firmware files,
with CONFIG_EXTRA_FIRMWARE_DIR, otherwise it will look in /lib/firmware.

So we'd need something like:

    $(if $(BR2_PACKAGE_LINUX_FIRMWARE),
        $(call KCONFIG_SET_OPT,CONFIG_EXTRA_FIRMWARE_DIR,"$${BR_BINARIES_DIR}/linux-firmware"))

(note the $$ escaping and the use of a shell-level variable, like is
done for CONFIG_INITRAMFS_SOURCE).

Regards,
Yann E. MORIN.

>  # Starting with 4.16, the generated kconfig paser code is no longer
>  # shipped with the kernel sources, so we need flex and bison, but
> -- 
> 2.20.1
> 
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