[Qemu-devel] Re: [PATCH 0/4] ppc: Fix PReP emulation

[Andreas Färber]

Am 19.12.2010 um 10:54 schrieb Alexander Graf:

> On 14.12.2010, at 01:49, Andreas Färber wrote:
>
> > Hello,
> >
> > Based on an earlier attempt of mine to make OpenBIOS work with -M  
> > prep,
> > with kind support from Hervé Poussineau here's an initial stab at
> > fixing the long-broken PReP emulation and preparing migration from
> > abandoned OpenHack'Ware to OpenBIOS as default FOSS firmware.
> >
> > In particular a number of hw_error()s are resolved, so that the BIOS
> > can be entered at all. It is not yet working in terms of serial and
> > VGA support etc.
> >
> > This series is also available from:
> >
> > git://repo.or.cz/qemu/afaerber.git prep-queue
> >
> > Some more work-in-progress for the curious is on my prep branch [2].
> > The corresponding work-in-progress OpenBIOS changes are at [3].
> >
> > Unfortunately the prep machine is lacking documentation what  
> > exactly it
> > tries to emulate. The plan thus is to merge emulation of a second,  
> > real
> > IBM 40p machine based on Hervé's work at [1], for use with original
> > binary firmware.
> >
> > Also upcoming are new ppc_chrp machines, forked from ppc_newworld,
> > emulating the 970-based IBM JS20 (using Apple U3) [4] and possibly  
> > the
> > POWER5-based IntelliStation 285. These depend on the ongoing ppc64  
> > port
> > of OpenBIOS to be completed though. This relates to PReP in that the
> > machine IDs will need to be coordinated.
>
> Does this series actually make anything work, or is it just a first  
> step set to get your development rolling? IOW, would users benefit  
> from having the patches upstream yet?

As indicated above, it lets you enter a BIOS, which is a user-visible  
improvement. User-supplied binary firmware works with 1 + 3-4, ELF  
firmware with 1-4. Patch 3 depends on review comments. Patch 4 was  
just an FYI for testing the preceding patches and still needs  
investigation.

For OpenBIOS to work, we need fw_cfg in ppc_prep.c and, independently,  
patches to OpenBIOS. Unless of course we want to use another firmware  
like OFW from the start. The main interest in PReP nowadays will be  
proprietary firmware anyway. I thought Rob (cc'ed) had PReP Linux  
kernel patches for QEMU at some point but I couldn't locate them in  
the Aboriginal Linux tree.

I am planning to queue reviewed patches for upstream on a new branch.  
Then we can either pull them into your ppc queue or directly into  
master.

Andreas