Daniel P. Berrange wrote: > On Tue, Aug 24, 2010 at 12:45:19PM +0200, Alexander Graf wrote: > >> Daniel P. Berrange wrote: >> >>> On Tue, Aug 24, 2010 at 12:02:30AM +0200, Alexander Graf wrote: >>> >>> >>>> The monitor command for hotplugging is in i386 specific code. This is just >>>> plain wrong, as S390 just learned how to do hotplugging too and needs to >>>> get drives for that. >>>> >>>> So let's add a generic copy to generic code that handles drive_add in a >>>> way that doesn't have pci dependencies. >>>> >>>> I'm not fully happy with the patch as is. IMHO there should only be a >>>> single target agnostic drive_hot_add function available. How we could >>>> potentially fit IF_SCSI in there I don't know though. >>>> >>>> >>> I'm not sure that this patch is actually neccessary. Via a undocumented, >>> sick, dirty hack, you can already use the current drive_add command >>> without a PCI address, for both virtio + scsi. In fact not using the >>> PCI address with drive_add is the preferred approach in the new qdev >>> world even on x86 >>> >>> >> It is certainly necessary since the current code is in a big fat #if >> defined(TARGET_I386) block :). >> > > True, true, killing the #ifdef is needed :-) >
And moving it out of the pci specific file. Yeah :). Basically my proposal was to take the patches as is and phase out the pci-hotplug.c version. > >>> The key is that you should use if=none for all cases. Here are two >>> examples of how libvirt does it currently: >>> >>> VirtIO: >>> >>> drive_add dummy >>> file=/var/lib/libvirt/images/data.img,if=none,id=drive-virtio-disk1,format=raw >>> device_add >>> virtio-blk-pci,bus=pci.0,addr=0x0,drive=drive-virtio-disk1,id=virtio-disk1' >>> >>> SCSI: >>> >>> drive_add dummy >>> file=/var/lib/libvirt/images/data.img,if=none,id=drive-scsi0-0-1,format=raw' >>> device_add >>> scsi-disk,bus=scsi0.0,scsi-id=1,drive=drive-scsi0-0-1,id=scsi0-0-1 >>> >>> The 'dummy' value there can be absolutely anything you want. >>> It is totaly ignored when QEMU sees if=none in 2nd arg. >>> >>> >> I'd be all for removing the pci-hotplug.c version of drive_add then. But >> I think the IF_SCSI option there is to append a drive to an existing >> SCSI bus, no? >> > > Actually this SCSI example I give above is appending a drive to an existing > bus (scsi0), in slot 1 (scsi-id=1). To best of my knowledge there is no > remaining use case that requires use of IF_SCSI, IF_IDE, etc. The IF_NONE > approach can cope with all, modulo bugs that appear periodically with code > that mistakenly checks for a particular IF_XXX constant. > > If you wanted to also create a new SCSI bus, before creating the drive on > it, you'd need to run three commands in total: > > device_add lsi,id=scsi0,bus=pci.0,addr=0x7 > drive_add dummy > file=/var/lib/libvirt/images/data.img,if=none,id=drive-scsi0-0-1,format=raw > device_add > scsi-disk,bus=scsi0.0,scsi-id=1,drive=drive-scsi0-0-1,id=scsi0-0-1 > Nice - so we can just deprecate if=!none? Alex
