qemu-mips illegal instruction

[Sean Bruno]

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


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