Re: [Qemu-devel] Re: playing with qemu usermode emulation on FreeBSD...

[Blue Swirl]

On Sat, Oct 17, 2009 at 1:34 AM, Juergen Lock <address@hidden> wrote:
> On Wed, Oct 14, 2009 at 12:19:32AM +0200, Juergen Lock wrote:
>> On Tue, Oct 13, 2009 at 12:20:58AM +0200, Juergen Lock wrote:
>> > On Mon, Oct 12, 2009 at 10:55:24PM +0300, Blue Swirl wrote:
>> > > On Mon, Oct 12, 2009 at 1:18 AM, Juergen Lock <address@hidden> wrote:
>> > > > On Thu, Oct 08, 2009 at 12:05:49AM +0200, Juergen Lock wrote:
>> > > >> I recently noticed there are x86 bsd-user targets now (yeah I totally
>> > > >> missed those commits...) and now got it working a tiny little bit:
>> > > >> I can run
>> > > >>       qemu-x86_64 -bsd freebsd /rescue/echo foo bar
>> > > >> here on FreeBSD 8/amd64 and it echoes foo bar as expected, but
>> > > >> segfaults afterwards. :)  (in pthread_setcancelstate() invoked from
>> > > >> a guest write() syscall, in case anyone is wondering.)  Other things
>> > > >> I tried either exit with errors or segfault as well, and i386 hosts
>> > > >> probably still don't work at all yet.  (qemu-i386 here on amd64 does
>> > > >> at least something, but probably needs lock_user() treatment for all
>> > > >> kinds of syscalls, I only tried adding that for sysctl so far.)
>> > > >>
>> > > >>  Anyway, here is an emulators/qemu-devel git head snapshot port
>> > > >> update with my current patches (files/patch-bsd-user), feel free to
>> > > >> test/debug/improve:
>> > > >>       http://people.freebsd.org/~nox/qemu/qemu-devel-20091007.patch
>> > > >> (For the folks reading this on the qemu list:  I shall start doing
>> > > >> `proper' patch submissions later, this is more for the FreeBSD folks
>> > > >> and because I was asked to send what I have...)
>> > > >
>> > > > New version at the same place, which now runs FreeBSD/{i386,sparc64}
>> > > > /rescue/echo on FreeBSD/amd64, the FreeBSD/amd64 target now segfaults
>> > > > in pthread_setcancelstate() invoked from the final writev() tho.
>> > > > Oh and I also uploaded the snapshot tarball so others can now actually
>> > > > build the port too... :)  And I have switched to the cpu-exec.c patch
>> > > > posted by Aleksej Saushev on the qemu list and added back amd64
>> > > > code there.
>> > > >
>> > > >  Here is the bsd-user patch again:
>> > >
>> > > Please add Signed-off-by: line and use 'diff -u' (or preferably git 
>> > > diff).
>> > >
>> > Well I wasn't expecting this diff to be committed just yet anyway,
>> > it's still more a wip version...
>> >
>> > > > +    if (1 /* bsd_type == target_freebsd */)
>> > > > +        regs->rdi = infop->start_stack;
>> > >
>> > > Why the if and comment?
>> > >
>> > > > +        if (1 /* bsd_type == target_freebsd */) {
>> > > > +            regs->u_regs[8] = infop->start_stack;
>> > > > +            regs->u_regs[11] = infop->start_stack;
>> > >
>> > > Same here.
>> > >
>> >  Because bsd_type isn't available at these places in the code but
>> > probably should be checked, I still wanted to fix that.  (Maybe
>> > make it global?)
>> >
>> I still haven't fixed this...
>>
>> > > >         case 0x100:
>> > > > +        /* FreeBSD uses 0x141 for syscalls too */
>> > > > +        case 0x141:
>> > > > +            if (bsd_type != target_freebsd)
>> > > > +                goto badtrap;
>> > >
>> > > You are now also trapping on case 0x100 if bsd_type != target_freebsd,
>> > > which probably breaks other BSDs.
>> > >
>> >  Right, thats broken, the 0x141 case should come before the 0x100
>> > here of course.
>> >
>>  ...but this I just fixed, and I added the multiboot.S patch, and
>> fixed the port's cdrom dma disable knob (files/cdrom-dma-patch).
>> (And I added the cpu-exec.c whitspace fix that was already in the
>> patch I posted in the BSD support thread.)
>>
>>  New version at the same place,
>>       http://people.freebsd.org/~nox/qemu/qemu-devel-20091007.patch
>> and I now also made a shar of the patched port:
>>       http://people.freebsd.org/~nox/qemu/qemu-devel-20091007.shar
>
> Updated again, among other things I added basic FreeBSD sysarch(2)
> handling, fixed syscall errno return (I had added code to set the
> carry bit for the x86 target before but the sign of the returned errno
> was still wrong), and I finally fixed the if (1) above (made bsd_type
> global.)
>
>  And, I now can run FreeBSD/amd64 /bin/sh and vim on same! :)  (zsh
> not yet tho.)
>
>  Oh and Toni tested taking FreeBSD/i386's default linker script,
> changing only the load address to 0x60000000 as in qemu's and,
> using that as i386.ld, he now can run qemu-i386 on FreeBSD/i386 with
> simple executables too...  See files/patch-bsd-user-ld in the shar,
> which I also now moved the x86_64.ld patch to that I had talked about
> earlier.  It probably can't be used everywhere as is tho since it has:
>        OUTPUT_FORMAT("elf32-i386-freebsd", "elf32-i386-freebsd",
>                      "elf32-i386-freebsd")
> (and I also don't know if the one currently in the tree has other
> features that are needed at least on Linux, any linker gurus care
> to comment?)
>
>  Here is the rest of the bsd-user patches again (files/patch-bsd-user
> in the shar), if you think they are ready to commit I'm not against it
> anymore :), comments are also welcome of course.

Thanks, applied. I made up a short commit message.