Re: [Qemu-devel] Small powerpc system emulation problem with linux

[Aurelien Jarno <aurelien@aurel32.net>]

On Wed, Jan 14, 2009 at 11:21:40AM -0500, Lennart Sorensen wrote:
> I did a subversion checkout of qemu last week and built it, and no
> problems with that part so far.
>
> I noticed it now supports using openbios-ppc32 instead of openhackware,
> so I went looking for that and did a subversion checkout of openbios
> and the fcode tools.  I used the openbios-elf ppc object as openbios-ppc32
> and qemu seems quite happy with that.

First of all, please retry with the current SVN, a lot of things have
been fixed.

> I then booted a debian 4.0 (etch) install cd, but the network interface
> didn't work (it gave a dumb error about the PCI bar 0 which was clearly
> wrong).  I then grabbed a daily build of debian 5.0 (lenny) instead, and
> booted that, and then networking worked fine.  I installed debian, and
> had no problems until I hit installing the bootloader.

This is a known problem, looks like there is a problem with IO ports. You
can workaround the problem by using an other card, like e1000.

> Debian tried to isntall the quik boot loader for oldworld mac's since
> that is what /proc/cpuinfo in linux claims to see, even though powermac
> g3 blue&white boxes (I have one here) is newworld, as are all powermac's
> using openfirmware 3.  newworld systems should use yaboot, but of course
> the installer had not setup the partitions for yaboot since it didn't
> see a newworld machine, and yaboot's installer refused to run since it
> wasn't a newworld machine.  quik boot's installer also refused to run
> since it wasn't a supported oldworld machine either.

The machine that is emulated is actually a g3beige, that is an OldWorld
machine. Installing quik on such machine is correct. Note that the
current version of debian installer installs a totally buggy quik.conf
file. It has to be fixed manually.

> So I managed to lie to yaboot enough to convince it to run the ofpath
> tools and such as if it was a newworld machine, and that all worked
> fine, other than failing to access some part of nvram as far as I can
> tell.
> 
> On rebooting I found that yaboot loaded from the disk, but failed to
> load the system.  Turns out debian uses an ancient version of yaboot
> that doesn't correctly work on some newer systems, and has issues with
> initrd images.  I found a newer binary for yaboot and replaced it in the
> bootstrap partition using a loopback mount.  After doing this, it
> finally loaded and booted.  I now have a working debian system on qemu.

Quik is now working correctly with the current SVN.

> So the main problems seem to be that the openbios firmware doesn't
> include an entry for 'interrupt-controller' which is the entry the linux
> kernel looks for to device a machine is newworld rather than oldworld in
> the powermac setup.  The other is that debian's yaboot is out of date.

No, this is actually normal, as an OldWorld machine is emulated.

> The yaboot problem is being worked on.
> 
> So now I am wondering what has to be done to make qemu appear as a
> newworld mac, since that is what the machine it claims to emulate is.
> Is this simply a mistake in openbios for qemu or does qemu actually
> emulate oldworld to some extent?

The machine in ppc_oldworld.c is an OldWorld machine. There has been
some mistakes in both OpenBIOS and QEMU, that should now be fixed.

We plan to emulated a NewWorld machine using ppc_chrp.c as a basis when
all the problem with the OldWorld machine have been solved.

-- 
  .''`.  Aurelien Jarno	            | GPG: 1024D/F1BCDB73
 : :' :  Debian developer           | Electrical Engineer
 `. `'   aurel32@debian.org         | aurelien@aurel32.net
   `-    people.debian.org/~aurel32 | www.aurel32.net