Re: [Qemu-devel] [libvirt] QEMU 1.6 and drive discard parameter

[Amos Kong <akong@redhat.com>]

On Thu, Oct 31, 2013 at 04:07:15PM +0800, Osier Yang wrote:
> CC to Amos.
> 
> On 30/10/13 16:19, whitearchey wrote:
> >
> >In QEMU 1.6 parameters of 'drive' option were removed:
> >
> >QemuOptsList qemu_drive_opts = {
> >    .name = "drive",
> >    .head = QTAILQ_HEAD_INITIALIZER(qemu_drive_opts.head),
> >    .desc = {
> >        /*
> >         * no elements => accept any params
> >         * validation will happen later
> >         */
> >        { /* end of list */ }
> >    },
> >};
> >
> >But libvirt still checks for QEMU_CAPS_DRIVE_DISCARD using QMP
> >query-command-line-options:
> >
> >static struct virQEMUCapsCommandLineProps virQEMUCapsCommandLine[] = {
> >    { "machine", "mem-merge", QEMU_CAPS_MEM_MERGE },
> >    { "drive", "discard", QEMU_CAPS_DRIVE_DISCARD },
> >    { "realtime", "mlock", QEMU_CAPS_MLOCK },
> >};
> >...
> >qemuMonitorGetCommandLineOptionParameters(mon,
> >virQEMUCapsCommandLine[i].option, &values)
> >
> >So, when I try to use discard option in domain xml I get this error:
> >
> >error : qemuBuildDriveStr:3986 : unsupported configuration:
> >discard is not supported by this QEMU binary
> >
> 
> It's a qemu problem, the command "query-command-line-options" should
> keep working
> after the structures were changed for any option, in this case, all
> the option descs were
> moved to "qemu_common_drive_opts" instead.

{ 'execute': 'query-command-line-options', 'arguments': { 'option': 'drive' } }
 
{
    "return": [
        {
            "parameters": [
            ],
            "option": "drive"
        }
    ]
}

It returns a NULL parameters list, that's true, some error handling
should be done by libvirt.

> Regards,
> Osier

-- 
			Amos.