On Tue, Mar 15, 2011 at 7:47 AM, Alexander Graf <ag...@suse.de> wrote: > > On 15.03.2011, at 08:09, Stefan Hajnoczi wrote: > >> On Mon, Mar 14, 2011 at 10:57 PM, Guido Winkelmann >> <guido-k...@thisisnotatest.de> wrote: >>> On Monday 14 March 2011 20:32:23 Stefan Hajnoczi wrote: >>>> On Mon, Mar 14, 2011 at 6:05 PM, Guido Winkelmann >>>> >>>> <guido-k...@thisisnotatest.de> wrote: >>>>> Does anybody have an idea what might cause this or what might be done >>>>> about it? >>>> >>>> The lsi_scsi emulation code is incomplete. It does not handle some >>>> situations like the ORDERED commands or message 0x0c. >>>> >>>> There is a patch to address the message 0xc issue, it has not been >>>> applied to qemu.git or qemu-kvm.git yet: >>>> http://patchwork.ozlabs.org/patch/63926/ >>>> >>>> Basically there is no one actively maintaining or reviewing patches >>>> for the lsi53c895a SCSI controller. >>> >>> Does that mean that using the SCSI transport for virtual disks is officially >>> unsupported or deprecated or that it should be? >> >> The LSI SCSI emulation in particular has not seen much attention. As >> for the wider SCSI emulation there has been work over the past few >> months so it's alive and being used. >> >>> Are things better with the IDE driver? >> >> IDE is commonly used for compatibility with guests that do not have >> virtio-blk drivers. It should work fine although performance is poor >> due to the IDE interface. >> >>>> virtio-blk works very will with Linux guests. Is there a reason you >>>> need to use SCSI emulation instead of virtio-blk? >>> >>> I can probably use virtio-blk most of the time, I was just hoping to be able >>> to virtualize a wider array of operating systems, like the *BSDs, >>> (Open)Solaris, Windows, or even just some linux distributions whose >>> installers >>> don't anticipate KVM and thus don't support virtio-<anything>. >> >> Windows virtio-blk drivers are available and should be used: >> http://www.linux-kvm.org/page/WindowsGuestDrivers/Download_Drivers >> >> BSD and Solaris don't ship with virtio-blk AFAIK. > > This is pretty much the gap that AHCI is trying to fill. It's a > well-supported HBA that pretty much every OS supports, but is still simple > enough to implement. Unfortunately, 0.14 ships without BIOS support for it, > so you can't boot off an AHCI disk yet. But as of 0.15, AHCI is pretty much > the adapter of choice for your use case. > > Please keep in mind that I didn't get FreeBSD rolling with AHCI emulation > yet. OpenBSD works just fine.
I think one missing AHCI feature was legacy PATA mode? Perhaps that is a good GSoC project if you're willing to mentor it, Alex. I'm thinking that with complete AHCI and legacy mode it would be a good choice as the default non-virtio-blk disk interface. Stefan -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
