[Buildroot] [PATCH] glibc: needs kernel headers >= 4.5 on mips(64)

[Yann E. MORIN]

Thomas, Romain, Vicente, All,

On 2017-08-20 22:26 +0200, Thomas Petazzoni spake thusly:
> On Sun, 20 Aug 2017 16:41:54 +0200, Romain Naour wrote:
> > I tried to use BR2_MIPS_NAN_2008 but it trigger a circular dependency in Kconfig.
> I indeed tried:
[--SNIP--]
> And Kconfig yells with:
> 
> toolchain/toolchain-buildroot/Config.in:23:error: recursive dependency detected!
> toolchain/toolchain-buildroot/Config.in:23:	choice <choice> contains symbol BR2_TOOLCHAIN_BUILDROOT_GLIBC
> toolchain/toolchain-buildroot/Config.in:43:	symbol BR2_TOOLCHAIN_BUILDROOT_GLIBC depends on BR2_MIPS_NAN_2008
> arch/Config.in.mips:168:	symbol BR2_MIPS_NAN_2008 is selected by BR2_MIPS_ENABLE_NAN_2008
> arch/Config.in.mips:185:	symbol BR2_MIPS_ENABLE_NAN_2008 is part of choice <choice>
> arch/Config.in.mips:171:	choice <choice> contains symbol <choice>
> arch/Config.in.mips:171:	choice <choice> contains symbol BR2_TOOLCHAIN_HAS_MNAN_OPTION
> toolchain/toolchain-common.in:347:	symbol BR2_TOOLCHAIN_HAS_MNAN_OPTION depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_9
> toolchain/toolchain-common.in:314:	symbol BR2_TOOLCHAIN_GCC_AT_LEAST_4_9 is selected by BR2_TOOLCHAIN_GCC_AT_LEAST_5
> toolchain/toolchain-common.in:318:	symbol BR2_TOOLCHAIN_GCC_AT_LEAST_5 is selected by BR2_TOOLCHAIN_GCC_AT_LEAST_6
> toolchain/toolchain-common.in:322:	symbol BR2_TOOLCHAIN_GCC_AT_LEAST_6 is selected by BR2_TOOLCHAIN_GCC_AT_LEAST_7
> toolchain/toolchain-common.in:326:	symbol BR2_TOOLCHAIN_GCC_AT_LEAST_7 is selected by BR2_GCC_VERSION_7_X
> package/gcc/Config.in.host:68:	symbol BR2_GCC_VERSION_7_X is part of choice <choice>
> package/gcc/Config.in.host:3:	choice <choice> contains symbol BR2_GCC_VERSION_4_9_X
> package/gcc/Config.in.host:23:	symbol BR2_GCC_VERSION_4_9_X depends on BR2_TOOLCHAIN_USES_MUSL
> toolchain/Config.in:25:	symbol BR2_TOOLCHAIN_USES_MUSL is selected by BR2_TOOLCHAIN_BUILDROOT_MUSL
> toolchain/toolchain-buildroot/Config.in:75:	symbol BR2_TOOLCHAIN_BUILDROOT_MUSL is part of choice <choice>
[--SNIP--]
> And I believe he is right to yell about this. I think the addition of
> the BR2_TOOLCHAIN_HAS_<xyz>_OPTION dependencies in arch/Config.in.mips
> is what causes the problem. Indeed, it's the first time we have a
> dependency on an architecture option to a toolchain option. This is not
> logical, because in Buildroot, you first select the architecture, and
> then you select the toolchain details. For example, we disallow
> selecting a given gcc version if it is not supported on a given
> architecture. But here, those BR2_TOOLCHAIN_HAS_MFPXX_OPTION /
> BR2_TOOLCHAIN_HAS_MNAN_OPTION are doing the opposite: they prevent you
> from selecting a given architecture variant if the gcc version is not
> sufficient.
> 
> I believe we need to invert those dependencies, and instead have a
> mechanism where selecting a too old gcc version is not possible when
> -mnan/-mfp are used on MIPS.

Agreed.

> Yann is specifically working on a mechanism to allow architectures to
> describe what minimum gcc version they need. Perhaps we should use that
> to express this dependency as well. Adding Yann in Cc :)

And indeed, it was pretty trivial to do so with my changes:
    https://git.buildroot.org/~ymorin/git/buildroot/commit/?h=yem/aarch64-cpus-2&id=96c77a38f423fd1745ea5601b71d3ac63c7ea11e
which allowed for:
    https://git.buildroot.org/~ymorin/git/buildroot/commit/?h=yem/aarch64-cpus-2&id=81fb80dc8fc8b93754cc068552a1eae917f14842

Also, I think we should rename BR2_TOOLCHAIN_HAS_MNAN_OPTION to include
the fact that it is mips, like: BR2_TOOLCHAIN_HAS_MIPS_MNAN_OPTION.

Ditto BR2_TOOLCHAIN_HAS_MFPXX_OPTION, BR2_TOOLCHAIN_HAS_MIPS_MFPXX_OPTION.

Regards,
Yann E. MORIN.

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