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
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