[Buildroot] [PATCH] package/linux-headers: with headers from kernel, also override srcdir

[Arnout Vandecappelle]

On 27/01/2021 22:24, Yann E. MORIN wrote:
> When using the headers from the kernel to be built, with the kernel
> set to a custom version, and overriding the kernel sources with
> LINUX_OVERRIDE_SRCDIR, the linux-headers package is still trying to
> download an archive, and fails to validate its hash.
> 
> What is going on under the hood is that, with _OVERRIDE_SRCDIR, the
> _VERSION of a package is set to 'custom'. Furthermore, the variable
> BR_NO_CHECK_HASH_FOR is recursively expanded, so its value is only
> evaluated when it is needed.
> 
> For linux-headers, we inherit the values from the linux package, and
> the LINUX_HEADERS_VERSION takes the value from the configuration.
> 
> Thus we end up with the following situation:
> 
>     LINUX_VERSION=custom
>     LINUX_HEADERS_VERSION=5.10   # For example
>     BR_NO_CHECK_HASH_FOR=... linux-custom.tar.gz ...
> 
> And thus the archive downloaded by linux-headers will not match any
> exclusion, and since there will most probably not be a hash for it,
> the download will fail, as was noticed and reported by Jarkko.
> 
> But in this case, what we really want is to really use the headers
> from the kernel that we build, we do not even want to attempt a
> download at all.
> 
> So, when using the headers from the kernel to be built, we also
> propagate the LINUX_OVERRIDE_SRCDIR to linux-headers, so that we
> also use the headers from the overridden sources.
> 
> Furthermore, in that configuration, we explicitly disallow
> overriding the linux-headers specifically, as it does not make sense
> (even though, if they were overridden to the same location, that'd
> be OK, but to simplify the condition, we do not even check for that).

 It's likely that some people that are currently using this configuration will
have explicitly set LINUX_HEADERS_OVERRIDE_SRCDIR as well to overcome this
problem, so this error will cause a regression for them.

 That said, it's easy enough to fix and the error message is clear, so I guess
it's OK.

 Applied to master, thanks.

 Regards,
 Arnout

 PS: No spelling errors, congratulations! :-)

> 
> Reported-by: Jarkko Sakkinen <jjs at kapsi.fi>
> Signed-off-by: Yann E. MORIN <yann.morin.1998 at free.fr>
> Cc: Thomas Petazzoni <thomas.petazzoni at bootlin.com>
> Cc: Peter Korsgaard <peter at korsgaard.com>
> Cc: Arnout Vandecappelle <arnout at mind.be>
> ---
>  package/linux-headers/linux-headers.mk | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/package/linux-headers/linux-headers.mk b/package/linux-headers/linux-headers.mk
> index 807e574f4d..a8d1c2ccaf 100644
> --- a/package/linux-headers/linux-headers.mk
> +++ b/package/linux-headers/linux-headers.mk
> @@ -18,6 +18,10 @@ LINUX_HEADERS_VERSION = $(call qstrip,$(BR2_LINUX_KERNEL_VERSION))
>  LINUX_HEADERS_CUSTOM_TARBALL_LOCATION = $(call qstrip,$(BR2_LINUX_KERNEL_CUSTOM_TARBALL_LOCATION))
>  LINUX_HEADERS_REPO_URL = $(call qstrip,$(BR2_LINUX_KERNEL_CUSTOM_REPO_URL))
>  LINUX_HEADERS_CIP = $(BR2_LINUX_KERNEL_LATEST_CIP_VERSION)$(BR2_LINUX_KERNEL_LATEST_CIP_RT_VERSION)
> +ifneq ($(LINUX_HEADERS_OVERRIDE_SRCDIR),)
> +$(error LINUX_HEADERS_OVERRIDE_SRCDIR must not be set when BR2_KERNEL_HEADERS_AS_KERNEL=y)
> +endif
> +LINUX_HEADERS_OVERRIDE_SRCDIR = $(LINUX_OVERRIDE_SRCDIR)
>  else # ! BR2_KERNEL_HEADERS_AS_KERNEL
>  LINUX_HEADERS_CUSTOM_TARBALL = $(call qstrip,$(BR2_KERNEL_HEADERS_CUSTOM_TARBALL))
>  LINUX_HEADERS_CUSTOM_GIT = $(call qstrip,$(BR2_KERNEL_HEADERS_CUSTOM_GIT))
>