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Re: [libvirt] [PATCH] Add support for qxl.revision in domain XML



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?
 - 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.

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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