On 6/26/07, Gregory Haskins <[EMAIL PROTECTED]> wrote: > On Mon, 2007-06-25 at 18:08 -0400, Avi Kivity wrote: > > > Note that there is another standard that would allow us to use built-in > > > routing without ACPI/IOAPIC: MSI. I know the battle over > > > virtual-bus-rendering is still raging w.r.t. to PCI or not-PCI. But I > > > will point out that if we do use PCI, setting the PV devices up as MSI > > > capable in the config space potentially eliminates the need to also wire > > > them to an IOAPIC. They will get their vector data from the MSI setup > > > and can then send APIC messages directly. (I think there is some > > > confusion about how we can do MSI later in this thread...I will reply to > > > those mails separately) > > > > > > > MSI is also a good solution; but do all semi-modern guest OSes support it? > > I can't say for sure, but I would guess "yes" because IIUC PCI-Express > only uses MSI (or at least heavily prefers it).
AFAIK for PCI-E devices MSI support is mandated by the standard. OTHO there's also the INTx emulation (the device *always* uses a write transaction to signal the interrupt condition, and the host bridge may turn the message into a legacy interrupt) so that the OS can drive the device even without fiddling with MSI. As Eddie said XP probably would be confused by MSI-only devices. Luca ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
