On 15.03.2011, at 10:03, Stefan Hajnoczi wrote: > On Tue, Mar 15, 2011 at 7:47 AM, Alexander Graf <[email protected]> wrote: >> >> On 15.03.2011, at 08:09, Stefan Hajnoczi wrote: >> >>> On Mon, Mar 14, 2011 at 10:57 PM, Guido Winkelmann >>> <[email protected]> wrote: >>>> On Monday 14 March 2011 20:32:23 Stefan Hajnoczi wrote: >>>>> On Mon, Mar 14, 2011 at 6:05 PM, Guido Winkelmann >>>>> >>>>> <[email protected]> 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.
AHCI can't runtime switch between AHCI mode and legacy mode, so I don't see the point in implementing the PATA mode counterparts? Alex -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
