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

[Rob Landley <rob@landley.net>]

On Sunday 19 December 2010 09:34:24 Alexander Graf wrote:
> On 19.12.2010, at 16:04, Andreas Färber wrote:
> > 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'm not sure on the copyright problems we might run into when delivering
> binary firmware. So we certainly do need some open source firmware solution
> for prep to at least have Linux running. For other guests, I don't see a
> reason why users shouldn't try to fetch a real firmware blob separately :).

Milton Miller wrote the ppc_bin in the last message from scratch, and made it 
available to me under GPLv2.  The tarball is the source (which includes a 
snapshot of dtc, which these days you can suck out of the linux kernel) and 
the .bin file is the output.  I used my own powerpc toolchain (built by the 
build scripts in the same source tree) to compile it.

Rob
-- 
GPLv3: as worthy a successor as The Phantom Menace, as timely as Duke Nukem 
Forever, and as welcome as New Coke.