Hi, >>> '-machine q35,diskmode=ahci,ide,raid'? >> >> I'm wondering whenever we want to deal with that at all? >> >> "If your guest is too old to handle ahci natively, just stick to piix." >> is a sensible policy IMHO. >> > > There was some discussion of trying to make q35 the default for 1.4, in > which case it may be important to support older OS's such as WinXP. > > Anthony, do you have any opinion on this?
The fundamental issue is that you have either good compatibility (makes old guests happy) or good performance (makes modern guests happy) by default. Picking a default which makes everybody happy is impossible. That problem doesn't change no matter whenever the choice is piix vs. q35 or q35+ide vs. q35+ahci. management apps (using libosinfo) can tackle this in a sensible manner by picking virtual hardware depending on the guest capabilities. So I wouldn't worry too much on qemu level. >>> 2) HPET ACPI error >>> >>> This line: 'IRQNoFlags () {2, 8}' in the HPET acpi table is causing the >>> folloing ACPI message (removing it makes it go away): >> >> Hmm. That was added to make macos x happy and is also present on real >> hardware, so I'm wondering what is going on here. >> > > I also noticed that on Windows 7, the 'IRQNoFlags' line above makes the RTC > clock complain that it does not have resources available. While removing the > above line, removes that error. Hmm. The IRQNoFlags for the RTC isn't new though, but I can see that with win7 on piix too. cheers, Gerd