Bug 1447831

Summary: don't parse/format vram attribute for cirrus video
Product: Red Hat Enterprise Linux Advanced Virtualization Reporter: Fangge Jin <fjin>
Component: libvirtAssignee: Jonathon Jongsma <jjongsma>
Status: CLOSED NOTABUG QA Contact: Lili Zhu <lizhu>
Severity: medium Docs Contact:
Priority: medium    
Version: 8.0CC: dyuan, kraxel, phrdina, rbalakri, xuzhang, zpeng
Target Milestone: rc   
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Hardware: x86_64   
OS: Linux   
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Last Closed: 2019-07-18 21:11:21 UTC Type: Bug
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Description Fangge Jin 2017-05-04 01:45:59 UTC
Description of problem:
   Set video type to cirrus, start vm, parameter "vgamem_mb" is not in qemu command line.

Version-Release number of selected component:
   libvirt-3.2.0-3.virtcov.el7.x86_64
   qemu-kvm-rhev-2.9.0-2.el7.x86_64

How reproducible:
   100%

Steps to Reproduce:
   1. Prepare a guest with the following xml:
   # virsh dumpxml rhel7-3
   ...
    <video>
      <model type='cirrus' vram='16384' heads='1' primary='yes'/>

   2. Start guest
   # virsh start rhel7-3

   3. Check qemu command line:
   # ps aux|grep cirrus
   ... -device cirrus-vga,id=video0,bus=pci.0,addr=0x2

Actual results:
   As step 3 

Expected results:
   vgamem_mb should be in qemu command line:
   ... -device cirrus-vga,id=video0,vgamem_mb=16,bus=pci.0,addr=0x2

Comment 2 Gerd Hoffmann 2017-10-06 11:58:18 UTC
> Expected results:
>    vgamem_mb should be in qemu command line:
>    ... -device cirrus-vga,id=video0,vgamem_mb=16,bus=pci.0,addr=0x2

No.  cirrus vga memory size isn't configurable.  Well, actually it is, but only for live migration backward compatibility reasons.  But in any case the amount of video memory usable by the guest is fixed at 4MB, period.

libvirt should not try to muck with vgamem_mb.

If anything libvirt should drop vram=... from xml for type=cirrus.

Comment 5 Jonathon Jongsma 2019-07-18 21:11:21 UTC
I proposed a patch to 'fix' this issue by essentially removing the parameter from the xml as suggested by Gerd above. But in the end, I decided that this wasn't really worth fixing since it's not really a bug.