[Buildroot] mips: nan2008 require kernel headers 4.5.x

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

Hello,

On Fri, 18 Aug 2017 12:54:19 +0200, Romain Naour wrote:

> Thomas replied on IRC:
> (23:16:16) kos_tom: Kubu: I know about this dependency
> (23:16:54) kos_tom: Kubu: we build our stable toolchains with 3.10
> (23:17:08) kos_tom: Kubu: except the mips32r5 toolchain that we build with
> kernel headers 4.9, see
> https://github.com/free-electrons/toolchains-builder/blob/master/configs/optionals/mips32r5el-glibc-stable.config
> 
> There is the same issue for mips32r5el and mips64r6el.
> 
> Actually it's not only mips, if you search "arch_minimum_kernel" in the glibc
> source code, you'll find few arch that require kernel header > 3.2
> 
> aarch64: kernel headers >= 3.7 (already handled in Buildroot)
> sysdeps/unix/sysv/linux/aarch64/configure.ac:arch_minimum_kernel=3.7.0

Where do you see that this is already handled in Buildroot ?

> ia64: kernel headers >= 3.2.18 (not supported in Buildroot)
> sysdeps/unix/sysv/linux/ia64/configure.ac:arch_minimum_kernel=3.2.18
> 
> mips with nan2008
> sysdeps/unix/sysv/linux/mips/configure.ac:if test -z "$arch_minimum_kernel"; then
> sysdeps/unix/sysv/linux/mips/configure.ac:    arch_minimum_kernel=4.5.0
> 
> nios2: kernel headers >= 3.19 (already handled in Buildroot)
> sysdeps/unix/sysv/linux/nios2/configure.ac:arch_minimum_kernel=3.19.0
> 
> powerpc64el: kernel headers >= 3.10 since glibc 2.26
> sysdeps/unix/sysv/linux/powerpc/powerpc64/configure.ac:  ],
> arch_minimum_kernel=3.10.0, libc_cv_ppc64_le=no)])
> 
> https://sourceware.org/git/?p=glibc.git;a=commit;h=c2ff5ec13fca1bdd1cd646a0260808386d7bd7ff
> 
> ia64: kernel headers >= 3.4.0 (not supported in Buildroot)
> sysdeps/unix/sysv/linux/x86_64/x32/configure.ac:arch_minimum_kernel=3.4.0
> 
> How to handle mips and powerpc64el kernel header dependency for glibc toolchains
> properly?

Well, just add more dependencies to BR2_TOOLCHAIN_BUILDROOT_GLIBC. What
is the problem with that ?

For example:

	depends on BR2_arm || BR2_armeb || \
		(BR2_aarch64 && BR2_TOOLCHAIN_HEADERS_AT_LEAST_3_7) || \
		...

and then:

comment "glibc on aarch64 needs a toolchain w/ headers >= 3.7"
	depends on BR2_aarch64
	depends on !BR2_TOOLCHAIN_HEADERS_AT_LEAST_3_7

> Maybe we can just don't allow building a mips toolchain with kernel headers <
> 4.5.0 and do the same for powerpc64el toolchains with kernel headers < 3.10.0 ?

Yes, see above.

Best regards,

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