On 08/19/2013 08:00 AM, anonym wrote:
Without knowing the exact development history of qemu, I assumed it could be the case the we have '-device' but 'usb-storage' hadn't been implemented yet (so '-usbdevice' was still the way to go).
No, if we have -device, the we MUST use it. Fallback to older code is possible only if -device is missing.
So, what if I drop the above chunk, and do the following instead:
--- a/src/qemu/qemu_command.c +++ b/src/qemu/qemu_command.c @@ -8046,18 +8046,26 @@ qemuBuildCommandLine(virConnectPtr conn,
/* Unless we have -device, then USB disks need special handling */ - if ((disk->bus == VIR_DOMAIN_DISK_BUS_USB) && - !virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE)) { - if (disk->device == VIR_DOMAIN_DISK_DEVICE_DISK) { - virCommandAddArg(cmd, "-usbdevice"); - virCommandAddArgFormat(cmd, "disk:%s", disk->src); + if (disk->bus == VIR_DOMAIN_DISK_BUS_USB) { + if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE)) { + if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE_USB_STORAGE)) { + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s", + _("This QEMU doesn't support '-device " + "usb-storage'")); + goto error; + }
This looks okay...
} else { - virReportError(VIR_ERR_INTERNAL_ERROR, - _("unsupported usb disk type for '%s'"), - disk->src); - goto error; + if (disk->device == VIR_DOMAIN_DISK_DEVICE_DISK) { + virCommandAddArg(cmd, "-usbdevice"); + virCommandAddArgFormat(cmd, "disk:%s", disk->src);
...but this still looks fishy (-device is so old that we are probably safer rejecting attempts to use a usb on a qemu that lacked -device than we are trying to figure out if -usbdevice worked for something that old - no one targetting a qemu that old will be trying to use new features anyway).
Alternatively, I could do the following instead, which is more concise, but doesn't happen in the same if() and thus spread the capability checking over a larger code area:
--- a/src/qemu/qemu_command.c +++ b/src/qemu/qemu_command.c @@ -4311,13 +4311,6 @@ qemuBuildDriveDevStr(virDomainDefPtr def, goto error; break; case VIR_DOMAIN_DISK_BUS_USB: + if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE_USB_STORAGE)) { + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s", + _("This QEMU doesn't support '-device " + "usb-storage'")); + goto error; + + }
That actually looks a bit nicer, even if it does spread the capability check across a wider set of code.
virBufferAddLit(&opt, "usb-storage");
if (qemuBuildDeviceAddressStr(&opt, def, &disk->info, qemuCaps) < 0)
Once I have an opinion (or further explanation why I'm still confused :)) I'll re-submit a new patchset with the preferred fix, rebased on the then-current master.
When resubmitting, send as a top-level patch (no in-reply-to) so it isn't buried, and use 'git send-email --subject-prefix=PATCHv2' or similar to make it obvious in the title that it is a rebased series. Good luck. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org