[Buildroot] [PATCH v2 1/3] toolchain: workaround musl/kernel headers conflict
Thomas Petazzoni
thomas.petazzoni at free-electrons.com
Wed Nov 16 22:30:01 UTC 2016
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 at 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
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