musl-cross toolchains now unusable in Buildroot

musl-cross toolchains now unusable in Buildroot

[Thomas Petazzoni]

Hello,

Since quite a while, we've added support in Buildroot for the pre-built
toolchains provided by musl-cross. This was a great way for people to
test very easily the musl C library, and therefore get more people to
use it.

We're currently using the 1.1.1 version of the toolchain.
Unfortunately, since version 1.1.2, two things have changed that
prevent us from using the pre-built toolchains:

 * 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.

   I've filled
   https://bitbucket.org/GregorR/musl-cross/issue/5/sysroot-support-needed-for-buildroot
   about this issue.

 * The absence of complete kernel headers. I don't know if it's related
   to the change to use the sanitized headers from the Sabotage
   project, or some other change, but the toolchain no longer has the
   <linux/...> directory, which normally contains files such as
   <linux/version.h>. This is for example causing a problem as
   Buildroot checks the kernel headers version using <linux/version.h>,
   though this particular aspect could potentially be fixed.

   I've filled
   https://bitbucket.org/GregorR/musl-cross/issue/6/non-standard-kernel-headers-causing-issues
   about this issue.

Feedback/comments welcome.

Thanks,

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

Re: musl-cross toolchains now unusable in Buildroot

[Bryan Hundven]

Thomas,

On Sun, Nov 9, 2014 at 11:56 AM, Thomas Petazzoni
<thomas.petazzoni@free-electrons.com> wrote:
> Hello,
>
> Since quite a while, we've added support in Buildroot for the pre-built
> toolchains provided by musl-cross. This was a great way for people to
> test very easily the musl C library, and therefore get more people to
> use it.
>
> We're currently using the 1.1.1 version of the toolchain.
> Unfortunately, since version 1.1.2, two things have changed that
> prevent us from using the pre-built toolchains:
>
>  * 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

>    I've filled
>    https://bitbucket.org/GregorR/musl-cross/issue/5/sysroot-support-needed-for-buildroot
>    about this issue.
>
>  * The absence of complete kernel headers. I don't know if it's related
>    to the change to use the sanitized headers from the Sabotage
>    project, or some other change, but the toolchain no longer has the
>    <linux/...> directory, which normally contains files such as
>    <linux/version.h>. This is for example causing a problem as
>    Buildroot checks the kernel headers version using <linux/version.h>,
>    though this particular aspect could potentially be fixed.
>
>    I've filled
>    https://bitbucket.org/GregorR/musl-cross/issue/6/non-standard-kernel-headers-causing-issues
>    about this issue.

I personally can't answer this one.

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

Cheers,

-Bryan

Re: musl-cross toolchains now unusable in Buildroot

[Thomas Petazzoni]

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

Re: musl-cross toolchains now unusable in Buildroot

[John Spencer]

Thomas Petazzoni wrote:
> Hello,
> 
> Since quite a while, we've added support in Buildroot for the pre-built
> toolchains provided by musl-cross. This was a great way for people to
> test very easily the musl C library, and therefore get more people to
> use it.
> 
> We're currently using the 1.1.1 version of the toolchain.
> Unfortunately, since version 1.1.2, two things have changed that
> prevent us from using the pre-built toolchains:
> 
>  * 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.
> 
>    I've filled
>    https://bitbucket.org/GregorR/musl-cross/issue/5/sysroot-support-needed-for-buildroot
>    about this issue.
> 
>  * The absence of complete kernel headers. I don't know if it's related
>    to the change to use the sanitized headers from the Sabotage
>    project, or some other change, but the toolchain no longer has the
>    <linux/...> directory, which normally contains files such as
>    <linux/version.h>. This is for example causing a problem as
>    Buildroot checks the kernel headers version using <linux/version.h>,
>    though this particular aspect could potentially be fixed.
> 
>    I've filled
>    https://bitbucket.org/GregorR/musl-cross/issue/6/non-standard-kernel-headers-causing-issues
>    about this issue.

there's already an issue filed here
https://github.com/GregorR/musl-cross/issues/30

Re: musl-cross toolchains now unusable in Buildroot

[Thomas Petazzoni]

Dear John Spencer,

On Tue, 11 Nov 2014 14:15:44 +0100, John Spencer 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.
> > 
> >    I've filled
> >    https://bitbucket.org/GregorR/musl-cross/issue/5/sysroot-support-needed-for-buildroot
> >    about this issue.
> > 
> >  * The absence of complete kernel headers. I don't know if it's related
> >    to the change to use the sanitized headers from the Sabotage
> >    project, or some other change, but the toolchain no longer has the
> >    <linux/...> directory, which normally contains files such as
> >    <linux/version.h>. This is for example causing a problem as
> >    Buildroot checks the kernel headers version using <linux/version.h>,
> >    though this particular aspect could potentially be fixed.
> > 
> >    I've filled
> >    https://bitbucket.org/GregorR/musl-cross/issue/6/non-standard-kernel-headers-causing-issues
> >    about this issue.
> 
> there's already an issue filed here
> https://github.com/GregorR/musl-cross/issues/30

Yes, I know. both issues are duplicated on bitbucket and github, and
it's not clear which of the two places is the official bug tracker for
musl-cross. I asked Gregor about this at
https://bitbucket.org/GregorR/musl-cross/issue/6/non-standard-kernel-headers-causing-issues,
but his reply was not very clear (at least not clear to me).

Best regards,

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