Re: musl-cross toolchains now unusable in Buildroot

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

Dear Bryan Hundven,

On Sun, 9 Nov 2014 12:05:23 -0800, Bryan Hundven wrote:

> >  * The toolchains have the sysroot mechanism disabled. For an unknown
> >    reason, in commit
> >    https://bitbucket.org/GregorR/musl-cross/commits/f9c0c3c34f0fe122541a129f1aa87686954d5f1b,
> >    the sysroot feature was disabled. This is weird, as essentially all
> >    modern toolchains have the sysroot feature enabled. This is
> >    essential for Buildroot to use a pre-built toolchain.
> 
> musl-cross uses a config.sh to configure the toolchain settings:
> https://bitbucket.org/GregorR/musl-cross/src/tip/config.sh?at=default
> 
> That is where you would set:
> ```
> WITH_SYSROOT=yes
> ```
> 
> So, musl-cross does still have sysroot, it just doesn't have it on by default.
> Sysroot support does have a problem with the path, which is described
> with this bug and patch:
> https://bitbucket.org/GregorR/musl-cross/issue/2/sysroot-configuration-bug

This is of zero interest for Buildroot. In Buildroot, we have two
mechanisms for toolchains:

 * What we call the "internal toolchain backend", where Buildroot
   builds its own toolchain. This already has the capability of
   building musl toolchains, and is completely independent from
   musl-cross (except from the fact that we borrowed the gcc patches).
   However, this "backend" forces the user to wait a fairly long time
   for the toolchain to build.

 * What we call the "external toolchain backend", where Buildroot
   simply downloads and uses an already existing pre-built toolchain.
   This is where the toolchains produced by musl-cross and available at
   https://e82b27f594c813a5a4ea5b07b06f16c3777c3b8c.googledrive.com/host/0BwnS5DMB0YQ6bDhPZkpOYVFhbk0/
   are nice, because Buildroot simply toolchains the tarball, extracts
   it and voila, we have a working Musl toolchain in a few seconds.

So, the fact that musl-cross *allows* to build sysroot-enabled
toolchain is of no use to us, if the toolchain proposed by musl-cross
at
https://e82b27f594c813a5a4ea5b07b06f16c3777c3b8c.googledrive.com/host/0BwnS5DMB0YQ6bDhPZkpOYVFhbk0/
don't have this option enabled.

Best regards,

Thomas

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