[Buildroot] [autobuild.buildroot.net] Build results for 2017-05-11

[Matthew Weber]

Thomas,

On Mon, May 15, 2017 at 2:23 AM, Thomas Petazzoni
<thomas.petazzoni at free-electrons.com> wrote:
> Hello,
>
> On Sun, 14 May 2017 22:03:27 -0500, Matthew Weber wrote:
>
>> > Well this is interesting and I'll have to dig around some more but
>> > here's what I've found after doing a build.  It looks like I have
>> > SPARC ELF ABI compatibility on my x86_64 Ubuntu 14.04.1 machine.  I
>> > can execute the test app since it's statically linked.
>> >
>> > # ./tryancilautoclose
>> > Unsupported ancillary data: 65535/1
>> > # echo $?
>> > 111
>> > # file tryancilautoclose
>> > tryancilautoclose: ELF 32-bit MSB  executable, SPARC version 1 (SYSV),
>> > statically linked, with unknown capability 0x41000000 = 0xf676e75,
>> > with unknown capability 0x10000 = 0x70403, not stripped
>>
>> Ok, didn't realize the qemu-user-static will automatically hook-up
>> support for executing the arch it supports seamlessly.  When I straced
>> I noticed the call into qemu-sparc-static.  Since removing that
>> package, I now observe what would be expected.
>
> Wow, ok. Thanks a lot for investigating this issue.
>
>> # ./tryancilautoclose
>> bash: ./tryancilautoclose: cannot execute binary file: Exec format error
>> # echo $?
>>  11126
>>
>> Sorry about that one Eric, it's fixed now on that machine and shouldn't reoccur.
>>
>> Thomas, should there be a check or warning added as part of
>> buildroot's package/host checking which would catch a case where
>> qemu-user-static is installed and may adversely affect the build?
>
> Yes, we should definitely do something about that. Ideally, Buildroot
> should do something to prevent binfmt_misc from kicking off the
> execution of foreign binaries. I have no idea if this is possible. If
> not, at the very least, we should warn/error out, but I really hate
> when a build system/tool asks me to change my system-wide configuration
> to operate correctly.
>

I looked at this a bit more, I think we could check for
/proc/sys/fs/binfmt_misc being mounted and then see if any qemu-*
files exist.  Beyond that I'm unsure of the action to take.
I think for autobuilder machines they should error out from the
autobuilder script as you'd want binfmts disabled (sudo update-binfmts
--disable) before that runs.  However for the normal shared use
server/build machine it does seem like an issue to enforce having that
disabled as a pre-req to doing a buildroot build. Maybe a check
initially at the beginning of make to warn the user.....

Matt