[Buildroot] [PATCH 1/1] buildroot-test: enable toolchains based on hostarch

[Matthew Weber]

Thomas,

On Wed, Mar 30, 2016 at 8:00 PM, Thomas Petazzoni
<thomas.petazzoni at free-electrons.com> wrote:
> Hello,
>
> On Wed, 30 Mar 2016 19:41:00 -0500, Matthew Weber wrote:
>
>> I guess I don't completely follow why "any arch" for the internals, as
>> that host arch entry should represent the arch of the system the
>> toolchain was built on, correct?  Or are you saying that because an
>> internal normally would be built from scratch it would work on any
>> arch?
>
> Precisely: internal toolchain configurations are configurations where
> the toolchain is built by Buildroot. Since it's built from scratch, the
> architecture of the machine on which we're running the build doesn't
> matter.

But for the autobuilder....  wondering how to distinguish host arch
then for internals...

>
>> If so, maybe we need a test that checks the gcc executable for
>> arch rather then using this host arch entry?
>
> The problem is that we need to know *before* choosing the toolchain
> configuration whether it will work or not on your machine. Otherwise,
> you'll pick up one of the toolchain configuration, generate a random
> set of packages, and then start the build. The build will start by
> downloading the external toolchain, will attempt to run the external
> toolchain gcc, which will fail and abort the build. Of course, at this
> point, we could detect if the failure is caused by the gcc not being
> for the right architecture, and instead of categorizing this failure as
> a build failure, simply move on and generate another configuration. But:
>
>  1/ This seems really wasteful.

Agreed

>
>  2/ It is not that trivial to distinguish build failures caused by the
>     compiler not being built for the right architecture from other
>     failures.
>
>> I do have a bug as we would still want to allow the i386 toolchains to
>> execute on a x86_64 system.  Currently it excludes those with this
>> update.
>
> Correct. i386 toolchains should be considered for x86_64 systems.

I'm thinking something like this in the get_toolchain _configs() that
adds the conditional to allow that.
...
    (_, _, _, _, hostarch) = os.uname()
    # ~2015 distros report x86 when on a 32bit install
    if hostarch == 'i686' or hostarch == 'i386' or hostarch == 'x86':
        hostarch = 'x86'
    # x86_64 defaults correctly, so not setting

    for row in csv.reader(l):
        config = {}
        config["url"] = row[0]
        config["hostarch"] = row[1]
        # Ignore toolchains that are not built for the appropriate
        # host architecture
        if hostarch != 'x86_64' and hostarch != config["hostarch"]:
            continue
        # Assuming x86_64 can also execute x86 toolchains
        if hostarch == 'x86_64' and config["hostarch"] != 'x86':
            continue
        config["libc"] = row[2]
        with urlopen_closing(config["url"]) as r:
            config["contents"] = decode_byte_list(r.readlines())
        configs.append(config)
    return configs

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



-- 
Thanks,
Matt