[libvirt] [PATCH 00/12] Autoselect a DRM node for egl-headless and add it to cmdline

[Ján Tomko]

On Thu, Nov 22, 2018 at 05:35:58PM +0100, Erik Skultety wrote:
>Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1628892.
>The problem is that we didn't put the DRI device into the namespace for QEMU to
>access, but that was only a part of the issue. The other part of the issue is
>that QEMU doesn't support specifying 'rendernode' for egl-headless yet (some
>patches to solve this are already upstream for 3.1, some are still waiting to
>be merged). Instead, QEMU's been autoselecting the DRI device on its own.
>There's no compelling reason for libvirt not doing that instead and thus
>prevent any permission-related issues.
>
>Unlike for SPICE though, I deliberately didn't add an XML attribute for users
>to select the rendernode for egl-headless, because:
>
>a) most of the time, users really don't care about which DRM node will be used
>and libvirt will most probably do a good decision
>

Picking a default does not conflict with displaying it in live XML.

>b) egl-headless is only useful until we have a remote OpenGL acceleration
>support within SPICE
>
>c) for SPICE (or for SDL for that matter at some point), the rendernode is
>specified as part of the <gl> subelement which says "if enabled, use OpenGL
>acceleration", but egl-headless graphics type essentially serves the same
>purpose, it's like having <gl enabled='yes'/> for SPICE, thus having a <gl>
>subelement for egl-headless type is rather confusing

Could be just <gl rendernode=''/>

Even if its usefulness is short-lived, not exposing this knob of the
domain while we do expose it for SPICE feels wrong.

Jano
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