Hi Martin,
> On 02/04/2013 04:16 PM, Christophe Fergeau wrote:
> > QXL devices have an associated 'revision' which is raised when
> > new features have been introduced which would break migration
> > to older versions. This commit makes it possible to set this
> > revision as QEMU sometimes support newer QXL revisions than what
> > it defaults to.
>
> This could help a lot, but few questions, if I may:
> - This only helps when the revision is specified, otherwise not,
> right?
If by "helps" you mean "changes the revision", then it's a bit more complex - the revision is determined by order of precedence by the following:
default
machine type (i.e. via -M)
global (which this patch sets)
> - Isn't there a way how to get the current supported (running)
> revision
> of QEMU's qxl video?
>
> If we don't know the current (and supported) revision, we are
> exposing a
> parameter we know completely nothing about and thus can only try to
> start qemu with it and wait if it initializes (I know that's how we
> do
> it with devices, but there's no other option). Transferring current
> revision during migration (even when unspecified) would help
> determining
> such errors before starting QEMU on destination.
>
> There's not much info about the revisions if you don't look in QEMU
> sources, so I'm not sure what our possibilities are. It's a good
> thing
> that the 'revision' parameter is supported since the same commit as
> qxl
> driver, though.
There is no "introspection" from the help, sorry. So like you said the only way to know what supported revisions are is to:
1) start a vm with -vga qxl as stopped, query the revision of the qxl device, you get R, then [1..R] are supported (i.e. inclusive)
2) to find out which higher revisions are supported, you'll have to start with each successive higher revision until you get an error code (you can wait for the machine start event, that is sent after all devices are initialized)
Of course we can fix qemu to report it now, but it won't help for any of the older versions..
>
> Few pointers inline...
>
> > ---
> > docs/formatdomain.html.in | 5 ++++-
> > docs/schemas/domaincommon.rng | 5 +++++
> > src/conf/domain_conf.c | 17
> > +++++++++++++++++
> > src/conf/domain_conf.h | 1 +
> > src/qemu/qemu_command.c | 8
> > ++++++++
> > .../qemuxml2argv-graphics-spice-compression.args | 3 ++-
> > .../qemuxml2argv-graphics-spice-compression.xml | 4 ++--
> > .../qemuxml2argv-graphics-spice-qxl-vga.args | 3 ++-
> > .../qemuxml2argv-graphics-spice-qxl-vga.xml | 4 ++--
> > tests/qemuxml2argvdata/qemuxml2argv-graphics-spice.args | 3 ++-
> > tests/qemuxml2argvdata/qemuxml2argv-graphics-spice.xml | 4 ++--
> > 11 files changed, 47 insertions(+), 10 deletions(-)
> >
> > diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
> > index 7ad8aea..4b269c8 100644
> > --- a/docs/formatdomain.html.in
> > +++ b/docs/formatdomain.html.in
> > @@ -3569,7 +3569,10 @@ qemu-kvm -net nic,model=? /dev/null
> > attribute <code>ram</code> (<span class="since">since
> > 1.0.2</span>) is allowed for "qxl" type only and specifies
> > the size of the primary bar, while <code>vram</code>
> > specifies the
> > - secondary bar size. If "ram" is not supplied a default
> > value is used.
> > + secondary bar size. If "ram" or "vram" are not supplied a
> > default
>
> Good fix, but it should in a be separate patch.
>
> > + value is used. The optional attribute
> > <code>revision</code> (<span
> > + class="since">since 1.0.3</span>) specifies the revision
> > of
> > + the QXL device, newer revisions provides more
> > functionality.
>
> s/provides/provide/ if I'm not mistaken
>
> > </dd>
> >
> > <dt><code>model</code></dt>
> > diff --git a/docs/schemas/domaincommon.rng
> > b/docs/schemas/domaincommon.rng
> > index 049f232..fc78e2d 100644
> > --- a/docs/schemas/domaincommon.rng
> > +++ b/docs/schemas/domaincommon.rng
> > @@ -2280,6 +2280,11 @@
> > <ref name="unsignedInt"/>
> > </attribute>
> > </optional>
> > + <optional>
> > + <attribute name="revision">
> > + <ref name="unsignedInt"/>
>
> This should be > 0 according to my experiments with qemu, but I
> believe
> we don't deal with such nuances in the RNG scheme.
>
> > + </attribute>
> > + </optional>
> > </group>
> > </choice>
> > <optional>
> > diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
> > index 5782abb..83be711 100644
> > --- a/src/conf/domain_conf.c
> > +++ b/src/conf/domain_conf.c
> > @@ -7391,6 +7391,7 @@ virDomainVideoDefParseXML(const xmlNodePtr
> > node,
> > char *vram = NULL;
> > char *ram = NULL;
> > char *primary = NULL;
> > + char *revision = NULL;
> >
> > if (VIR_ALLOC(def) < 0) {
> > virReportOOMError();
> > @@ -7406,6 +7407,7 @@ virDomainVideoDefParseXML(const xmlNodePtr
> > node,
> > ram = virXMLPropString(cur, "ram");
> > vram = virXMLPropString(cur, "vram");
> > heads = virXMLPropString(cur, "heads");
> > + revision = virXMLPropString(cur, "revision");
>
> You're leaking the revision string in here.
>
> >
> > if ((primary = virXMLPropString(cur, "primary"))
> > != NULL)
> > if (STREQ(primary, "yes"))
> > @@ -7456,6 +7458,19 @@ virDomainVideoDefParseXML(const xmlNodePtr
> > node,
> > def->vram = virDomainVideoDefaultRAM(dom, def->type);
> > }
> >
> > + if (revision) {
> > + if (def->type != VIR_DOMAIN_VIDEO_TYPE_QXL) {
> > + virReportError(VIR_ERR_XML_ERROR, "%s",
> > + _("revision attribute only supported
> > for type of qxl"));
> > + goto error;
> > + }
> > + if (virStrToLong_ui(revision, NULL, 10, &def->revision) <
> > 0) {
> > + virReportError(VIR_ERR_XML_ERROR,
> > + _("cannot parse video revision '%s'"),
> > revision);
> > + goto error;
> > + }
> > + }
> > +
> > if (heads) {
> > if (virStrToLong_ui(heads, NULL, 10, &def->heads) < 0) {
> > virReportError(VIR_ERR_INTERNAL_ERROR,
> > @@ -13406,6 +13421,8 @@ virDomainVideoDefFormat(virBufferPtr buf,
> > virBufferAsprintf(buf, " heads='%u'", def->heads);
> > if (def->primary)
> > virBufferAddLit(buf, " primary='yes'");
> > + if (def->revision)
> > + virBufferAsprintf(buf, " revision='%u'", def->revision);
> > if (def->accel) {
> > virBufferAddLit(buf, ">\n");
> > virDomainVideoAccelDefFormat(buf, def->accel);
> > diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
> > index 9a9e0b1..81925b1 100644
> > --- a/src/conf/domain_conf.h
> > +++ b/src/conf/domain_conf.h
> > @@ -1160,6 +1160,7 @@ struct _virDomainVideoDef {
> > unsigned int ram; /* kibibytes (multiples of 1024) */
> > unsigned int vram; /* kibibytes (multiples of 1024) */
> > unsigned int heads;
> > + unsigned int revision;
> > bool primary;
> > virDomainVideoAccelDefPtr accel;
> > virDomainDeviceInfo info;
> > diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
> > index f6273c1..e45c808 100644
> > --- a/src/qemu/qemu_command.c
> > +++ b/src/qemu/qemu_command.c
> > @@ -3598,6 +3598,9 @@ qemuBuildDeviceVideoStr(virDomainVideoDefPtr
> > video,
> >
> > /* QEMU accepts bytes for vram_size. */
> > virBufferAsprintf(&buf, ",vram_size=%u", video->vram *
> > 1024);
> > +
> > + if (video->revision != 0)
>
> you can drop the '!= 0' in here, but that's unimportant.
>
> > + virBufferAsprintf(&buf, ",revision=%u",
> > video->revision);
> > }
> >
> > if (qemuBuildDeviceAddressStr(&buf, &video->info, caps) < 0)
> > @@ -6631,6 +6634,11 @@ qemuBuildCommandLine(virConnectPtr conn,
> > virCommandAddArgFormat(cmd,
> > "%s.vram_size=%u",
> > dev, vram * 1024);
> > }
> > + if (def->videos[0]->revision) {
> > + virCommandAddArg(cmd, "-global");
> > + virCommandAddArgFormat(cmd,
> > "%s.revision=%u",
> > + dev,
> > def->videos[0]->revision);
> > + }
> > }
> > }
> >
> [...]
>
> I haven't checked the tests, but they don't fail, so that's good :)
>
> Martin
>
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