qemu-mips illegal instruction

[Warner Losh]

On Apr 4, 2014, at 4:40 PM, Sean Bruno <sbruno at ignoranthack.me> wrote:

> On Fri, 2014-04-04 at 11:11 -0700, Sean Bruno wrote:
>> On Fri, 2014-03-28 at 11:00 -0700, Sean Bruno wrote:
>>>> This problem seems to be caused by a endian issue in qemu-mips.  Ed
>>>> Maste found the culprit and I've applied it here:
>>>> 
>>>> https://github.com/seanbruno/qemu/commit/05ee8495804599b52a88eb36b13ea9c06b3207cd
>>>> 
>>>> Which is my combined tracking branch for qemu and sson's bsd-user
>>>> branch.
>>>> 
>>>> I'm currently tracking an "illegal instruction" on exit issue that seems
>>>> to happen on application exit causing a crash.
>>>> 
>>>> sean
>>> 
>>> 
>>> I've been tracking qemu upstream with sson's patches and massaging
>>> things here and there with the bsd-user mode qemu.
>>> 
>>> https://github.com/seanbruno/qemu/tree/bsd-user
>>> 
>>> That in combination with sson's kernelmod/userland tool allows me to
>>> "chroot" into a mips environment suitable for building packages.
>>> http://people.freebsd.org/~sson/imgact_binmisc/imgact_binmisc.diff
>>> 
>>> Currently, if I explicitly pass a shell into the chroot command, I have
>>> no issues and all is well.  e.g.  chroot /mipsbuild /bin/sh
>>> 
>>> If I do not explicitly pass a shell, I get an illegal instruction core
>>> dump from qemu-mips on exit from any command I run in the chroot:
>>> 
>>> chroot /mipsbuild
>>> uname -a
>>> <uname output>
>>> (Illegal Instruction)[coredump]
>>> 
>>> This breaks poudriere right now.
>>> 
>>> 
>>> More or less this is my recipe:
>>>      - built a mips32 world for "chroot" purposes:
>>>      - use sson's binmisc ELF interceptor thing:
>>>      - run binmiscctl:
>>> binmiscctl add mips32 --interpreter "/bin/qemu-mips" --magic "\x7f\x45
>>> \x4c\x46\x01\x02\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00
>>> \x08" --mask "\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff
>>> \xff\xff\xff\xfe\xff\xff" --size 20 --set-enabled
>>> 
>>> 
>>>      - chroot /mipsbuild
>>>      - uname -a (Illegal Instruction and coredump ON EXIT)
>>> 
>>>      - chroot /mipsbuild /bin/sh
>>>      - uname -a (works everytime)
>>> 
>>> 
>>> sean
>> 
>> I've narrowed this down with some help from #bsdmips:
>> 
>> env SHELL=/bin/sh chroot /mipsbuild  --> no issues running commands
>> 
>> env SHELL=/bin/csh chroot /mipsbuild
>> env SHELL=/bin/tcsh chroot /mipsbuild --> both of these cause illegal
>> instructions in qemu-mips
>> 
>> Juregen came up with a patch that makes the amd64 version of qemu-mips
>> work, so there's no need to xbuild the i386 version now, so thanks for
>> that!
>> 
>> sean
>> 
>> ref https://github.com/seanbruno/qemu/tree/bsd-user
>> 
>> 
> 
> 
> And finally, thanks to peter, we have a 1bit change for 32bit mips that
> seems to work.
> 
> https://github.com/seanbruno/qemu/commit/d62553b108aa27c0c020dbb771d29f8673807a3b
> 
> 
> Doing a test run now.  this might mean that 32bit mips packages might
> exist this weekend in some form.

Doesn’t that daddu turn into a simple addu with that bit change?

Warner