[Buildroot] [PATCH v2 1/3] toolchain: workaround musl/kernel headers conflict

[Thomas Petazzoni <thomas.petazzoni@free-electrons.com>]

Hello,

On Thu, 10 Nov 2016 15:27:11 +0200, Baruch Siach wrote:
> Rick Felker suggested[1] this hack as a workaround to musl libc conflict with
> kernel headers:
> 
>   The problem is linux/libc-compat.h, which should fix this, only works
>   on glibc, by design. See:
> 
>   #ifndef _LIBC_COMPAT_H
>   #define _LIBC_COMPAT_H
> 
>   /* We have included glibc headers... */
>   #if defined(__GLIBC__)
> 
>   /* Coordinate with glibc netinet/in.h header. */
>   #if defined(_NETINET_IN_H)
> 
>   If you patch it like this:
> 
>   -#if defined(__GLIBC__)
>   +#if 1
> 
>   then it should mostly work but it's still all a big hack. I think
>   that's what distros are doing. The problem is that the same header is
>   trying to do two different things:
> 
>   1. Provide extra linux-kernel-API stuff that's not in the
>      libc/userspace headers.
> 
>   2. Provide definitions of the standard types and constants for uClibc
>      and klibc, which don't have complete libc headers and rely on the
>      kernel headers for definitions.
> 
>   These two uses really should be separated out into separate headers so
>   that the latter only get included explicitly by uClibc and klibc and
>   otherwise remain completely unused. But that would require coordinated
>   changes/upgrades which are unlikely to happen. :(
> 
> Upstream musl still evaluates[2][3] a permanent solution.
> 
> With this in place we can revert (at least) commits a167081c5d (bridge-utils:
> fix build with musl) and e74d4fc4932 (norm: add patch to fix musl build).
> 
> [1] http://www.openwall.com/lists/musl/2015/10/08/2
> [2] http://git.musl-libc.org/cgit/musl/commit/?id=04983f2272382af92eb8f8838964ff944fbb8258
> [3] http://www.openwall.com/lists/musl/2016/11/09/2
> 
> Signed-off-by: Baruch Siach <baruch@tkos.co.il>
> ---
> v2:
>   * Add Rick's explanation in the commit log (Arnout)
>   * Link to more recent upstream changes
> ---
>  toolchain/toolchain/toolchain.mk | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)

Series applied to the next branch. Thanks!

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com