On a Friday in 2022, Jonathon Jongsma wrote:
Add the ability to enable blob resources for the virtio video device.
This will accelerate the display path due to less or no copying of pixel
data.
Blob resource support can be enabled with e.g.:
<video>
<model type='virtio' blob='on'/>
</video>
Some additional background information about blob resources:
https://lists.freedesktop.org/archives/dri-devel/2020-August/275972.html
https://www.kraxel.org/blog/2021/05/virtio-gpu-qemu-graphics-update/
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2032406
Signed-off-by: Jonathon Jongsma <jjongsma@xxxxxxxxxx>
---
docs/formatdomain.rst | 7 +++++++
src/conf/domain_conf.c | 6 ++++++
src/conf/domain_conf.h | 1 +
src/conf/domain_validate.c | 13 ++++++++++---
src/conf/schemas/domaincommon.rng | 5 +++++
5 files changed, 29 insertions(+), 3 deletions(-)
diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst
index e28b805009..b057fc4703 100644
--- a/docs/formatdomain.rst
+++ b/docs/formatdomain.rst
@@ -6346,6 +6346,13 @@ A video device.
:since:`since 1.3.3` ) extends secondary bar and makes it addressable as
64bit memory.
+ :since:`Since 8.10.0` (QEMU driver only), devices with type "virtio" have an
+ optional ``blob`` attribute that can be set to "on" or "off". Setting
+ ``blob`` to "on" will enable the use of blob resources in the device. This
+ can accelerate the display path by reducing or eliminating copying of pixel
+ data between the guest and host. Note that blob resource support requires
+ QEMU version 6.1 or newer.
+
:since:`Since 5.9.0` , the ``model`` element may also have an optional
``resolution`` sub-element. The ``resolution`` element has attributes ``x``
and ``y`` to set the minimum resolution for the video device. This
diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 7484059e47..adbb41d19e 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -12583,6 +12583,9 @@ virDomainVideoModelDefParseXML(virDomainVideoDef *def,
else if (rc == 0)
def->heads = 1;
+ if (virXMLPropTristateSwitch(node, "blob", VIR_XML_PROP_NONE, &def->blob) < 0)
+ return -1;
+
return 0;
}
@@ -24623,6 +24626,9 @@ virDomainVideoDefFormat(virBuffer *buf,
virBufferAsprintf(buf, " heads='%u'", def->heads);
if (def->primary)
virBufferAddLit(buf, " primary='yes'");
+ if (def->blob != VIR_TRISTATE_SWITCH_ABSENT)
+ virBufferAsprintf(buf, " blob='%s'",
+ virTristateSwitchTypeToString(def->blob));
Thankfully we abolished the strict 80 column rule, so this can fit on
one line.
https://libvirt.org/coding-style.html#code-formatting-especially-for-new-code
if (def->accel || def->res) {
virBufferAddLit(buf, ">\n");
virBufferAdjustIndent(buf, 2);
Reviewed-by: Ján Tomko <jtomko@xxxxxxxxxx>
Jano
