On Mon, Jun 18, 2012 at 03:52:34PM +0200, Markus Armbruster wrote: > Anthony Liguori <anth...@codemonkey.ws> writes: > > > On 06/15/2012 12:57 PM, Jason Baron wrote: > >> On Thu, Jun 14, 2012 at 03:16:03PM -0500, Anthony Liguori wrote: > >>> On 06/14/2012 02:54 PM, Jason Baron wrote: > >>>> Hi, > >>>> > >>>> I recently updated Isaku Yamahata's q35 patches to work on the latest > >>>> qemu and > >>>> seabios trees. On the qemu side, most of the changes revolved around > >>>> updating > >>>> to use QOM and updates to the memory API. I was also able to drop quite > >>>> a few > >>>> patches that had already been resolved by the current qemu tree. > >>>> > >>>> The trees seem pretty stable and can be found here: > >>>> > >>>> git://github.com/jibaron/q35-qemu.git > >>>> git://github.com/jibaron/q35-seabios.git > >>> > >>> I'm got the beginnings of a feature page started: > >>> > >>> http://wiki.qemu.org/Features/Q35 > >>> > >>> The approach above will not work in a QOM world unfortunately. We > >>> need to do quite a bit of ground work before adding another chipset. > >>> The biggest task is converting devices to not require an ISA bus > >>> since ICH9 simply doesn't have an ISA bus. > >>> > >> > >> Right, there is no h/w isa bus, but the LPC interface chip is modeled as > >> an isa > >> bridge. So having an isa bus hanging off of it doesn't seem unreasonable. > >> Unless > >> there is some more fundamental reason not do it this way? > >> > >> It hows up in lspci as: > >> > >> 00:1f.0 ISA bridge: Intel Corporation 82801IB (ICH9) LPC Interface > >> Controller (rev 02) > > > > It's not a question of ISA vs. LPC, it's which devices are actually on > > that bus. See my respond to Markus's note. > > Maybe I'm naive, but platform devices handing off an ISA bus provided by > that ICH9 ISA bridge looks like a fair approximation to me. Yes, the > actual wiring is LPC, but that's a hardware detail invisible to device > models and guest, isn't it? > > Of course, you can't connect anything but the platform devices to that > bus. To connect other ISA devices, you'd have to add a second ISA > bridge. I suspect that's what you meant by "You can still have a > PCI-ISA bridge but the SuperI/O chip is not part of it" elsewhere in > this thread. > > No idea whether such beasts exist in the physical world, and how they > work.
See a dump from an old machine of mine (thinkpad T500 FWIW): it does have an ISA bridge behind the root bus.
