[Buildroot] [PATCH] package/glibc: fix usage of BR2_PACKAGE_GLIBC_KERNEL_COMPAT

[Yann E. MORIN]

Guillaume, All,

On 2022-09-02 12:34 +0200, Guillaume Smaha spake thusly:
> As explain in the commit 525ffc2bb17fa11fc128124d2d3a92d8698eaab8:
> "Say 'y' here if you plan on running your system on a kernel older than
> the version used for the toolchain headers."
> 
> Signed-off-by: Guillaume Smaha <guillaume.smaha at gmail.com>
> ---
>  package/glibc/glibc.mk | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/package/glibc/glibc.mk b/package/glibc/glibc.mk
> index 5af539ca62..4e4417b45a 100644
> --- a/package/glibc/glibc.mk
> +++ b/package/glibc/glibc.mk
> @@ -98,7 +98,7 @@ endif
>  GLIBC_MAKE = $(BR2_MAKE)
>  GLIBC_CONF_ENV += ac_cv_prog_MAKE="$(BR2_MAKE)"
>  
> -ifeq ($(BR2_PACKAGE_GLIBC_KERNEL_COMPAT),)
> +ifeq ($(BR2_PACKAGE_GLIBC_KERNEL_COMPAT),y)

You may have gotten a bit confused, but the curent situation is exactly
correct.

Indeed, when configured _without_ passing any --enable-kernel=X.Y.Z
value, then glibc will enable *all* the backward compatibility wrappers.

However, when configured with --enable-kernel=X.Y.Z, then only those
wrappers needed for being compatible with that version of the kernel
will be used.

So, indeed, we do not want to pass --enable-kernel=X.Y.Z when
BR2_PACKAGE_GLIBC_KERNEL_COMPAT is set.

For more information, see:
    https://www.gnu.org/software/libc/manual/html_mono/libc.html#Configuring-and-compiling
    https://github.com/bminor/glibc/blob/master/configure.ac#L273
    https://github.com/bminor/glibc/blob/master/sysdeps/unix/sysv/linux/configure.ac#L30

Regards,
Yann E. MORIN.

>  GLIBC_CONF_OPTS += --enable-kernel=$(call qstrip,$(BR2_TOOLCHAIN_HEADERS_AT_LEAST))
>  endif
>  
> -- 
> 2.34.1
> 
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