Re: [OpenBIOS] [Qemu-devel] [PATCH 01/27] Clean up PowerPC SLB handling code

[Andreas Färber]

QEMU HEAD still uses a 32-bit binary for both 32-bit and 64-bit. That one uses mtsrin so will need the compatibility, it seemed affected, too.

OpenBIOS SVN HEAD (blob) uses slb* as linked to. We're in the preparation of 1.1 and I need to test it before we can update the QEMU binary. ;)

Sorry for top-posting, Android sucks.

Andreas

David Gibson  schrieb:
> On Thu, May 19, 2011 at 08:00:53AM +0200, Andreas Färber wrote:
> > Am 19.05.2011 um 07:39 schrieb David Gibson:
> > > On Thu, May 19, 2011 at 07:35:30AM +0200, Andreas Färber wrote:
> > > > Am 25.03.2011 um 04:21 schrieb David Gibson:
> > > > > Currently the SLB information when emulating a PowerPC 970 is
> > > > > storeed in a structure with the unhelpfully named fields 'tmp'
> > > > > and 'tmp64'.  While the layout in these fields does match the
> > > > > description of the SLB in the architecture document, it is not
> > > > > convenient either for looking up the SLB, or for emulating the
> > > > > slbmte instruction.
> > > > >
> > > > > This patch, therefore, reorganizes the SLB entry structure to be
> > > > > divided in the the "ESID related" and "VSID related" fields as
> > > > > they are divided in instructions accessing the SLB.
> > > > >
> > > > > In addition to making the code smaller and more readable, this will
> > > > > make it easier to implement for the 1TB segments used in more
> > > > > recent PowerPC chips.
> > > > >
> > > > > Signed-off-by: David Gibson
> > > >
> > > > According to my bisect, this patch broke ppc64 OpenBIOS.
> > > >
> > > > David, would you please take a look?
> > >
> > > Uh, sure.  can you describe the symptoms of the breakage, and the
> > > exact qemu setup you've observed the problem with?
> >
> > $ uname -a
> > Darwin PMG5-3.local 9.8.0 Darwin Kernel Version 9.8.0: Wed Jul 15
> > 16:57:01 PDT 2009; root:xnu-1228.15.4~1/RELEASE_PPC Power Macintosh
> > # Mac OS X 10.5.8 on dual-core G5
> >
> > $ gcc-4.2 --version
> > powerpc-apple-darwin9-gcc-4.2.1 (GCC) 4.2.1 (Apple Inc. build 5577)
> > Copyright (C) 2007 Free Software Foundation, Inc.
> > This is free software; see the source for copying conditions.  There
> > is NO
> > warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
> > PURPOSE.
> >
> > ../qemu/configure --prefix=/Users/andreas/QEMU/latest64 \
> > --target-list=ppc-softmmu,ppc64-softmmu \
> > --extra-cflags="-arch ppc64" --extra-ldflags="-arch ppc64" --cc=gcc-4.2
> > --host-cc=gcc-4.2 \
> > --enable-cocoa --disable-kvm --disable-strip --disable-docs
> > --enable-io-thread $*
> > # I/O thread doesn't matter
> >
> > /Users/andreas/QEMU/qemu64/ppc64-softmmu/qemu-system-ppc64 -boot d -cdrom
> > /Users/andreas/QEMU/AIX/dvd.1022A4_OBETA_710.iso \
> > -bios /Users/andreas/QEMU/OpenBIOS/openbios/obj-ppc64/openbios-qemu.elf
> > -m 1024 \
> > -M mac99 -prom-env 'auto-boot?=false' -nographic
> >
> > CD should be irrelevant, -boot c -hda /dev/null should work the same.
>
> Um, yeah, I thought putting an AIX dvd into a Mac was a bit odd.
> > Expected: OpenBIOS banner and > prompt
> > Observed: DSI exception on mtmsrd, no serial output
>
> Does this happen only with your openbios image, or does it also happen
> with the one included in qemu?
>
> My working theory is that openbios is using the old 32-64 bridge stuff
> where segment register accesses are emulated to populate certain SLB
> slots.  I have a vague recollection that I saw the code implementing
> that when I was doing the cleanup and convinced myself it was not
> necessary.  More information as I investigate further.
> > (The regression on ppc32 AIX observed by Kenneth seems to be a
> > different issue, introduced earlier.)
>
> I don't know what that regression is; I don't read qemu-devel
> exhaustively.  If you want my attention, best to CC me directly.