Bug 987097 - X w/ QXL fails to start on RHEL 5.8/5.9 guests, seavgabios seems to be the culprit
Summary: X w/ QXL fails to start on RHEL 5.8/5.9 guests, seavgabios seems to be the cu...
Alias: None
Product: Fedora
Classification: Fedora
Component: seabios
Version: 19
Hardware: x86_64
OS: Linux
Target Milestone: ---
Assignee: Fedora Virtualization Maintainers
QA Contact: Fedora Extras Quality Assurance
Depends On:
TreeView+ depends on / blocked
Reported: 2013-07-22 17:15 UTC by Dhiru Kholia
Modified: 2015-02-17 16:18 UTC (History)
12 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 2015-02-17 16:18:22 UTC

Attachments (Terms of Use)
old X fails to start under KVM (14.67 KB, text/x-log)
2013-07-22 17:15 UTC, Dhiru Kholia
no flags Details

Description Dhiru Kholia 2013-07-22 17:15:43 UTC
Created attachment 776978 [details]
old X fails to start under KVM

Description of problem:

X fails to start on RHEL / CentOS 5.8 guests running under KVM.

The X processes crashes during the installation and during the after installation boots.

This might not be a virt-manager bug (looks like a QEMU device emulation bug).

Version-Release number of selected component (if applicable):

Host is running updated Fedora 19 64-bit.

$ uname -r

$ rpm -qa | grep kvm

$ rpm -qa | grep virt-manager               

How reproducible:

Try to install RHEL / CentOS 5.8 under KVM.

Expected results:

X should be able to run as usual.

Comment 1 Cole Robinson 2013-07-29 17:56:51 UTC
I can reproduce too with the RHEL5.9 guest. Seems to be seavgabios related, the vgabios-qxl in qemu.git doesn't produce the issue. Emulator from F19 qemu 1.4.2 and qemu.git both reproduce with seabios.git using the build process we use for fedora seabios.

I'm reproducing with a PXE setup: when anaconda tries to transition to graphical mode there's errors about starting X and it continues on. Here's my command line:

/home/crobinso/src/qemu/x86_64-softmmu/qemu-system-x86_64 \
    -machine pc-1.2,accel=kvm,usb=off \
    -m 2048 -smp 2,sockets=2,cores=1,threads=1 \
    -boot order=n \
    -drive file=/mnt/data/devel/images/rhel5-latest.qcow2,if=none,id=drive-virtio-disk0,format=qcow2 -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x6,drive=drive-virtio-disk0,id=virtio-disk0 \
    -netdev bridge,br=virbr0,id=hostnet0 \
    -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:b3:ca:d1,bus=pci.0,addr=0x3 \
    -sdl \
    -vga qxl \
    -global qxl-vga.ram_size=67108864 \
    -global qxl-vga.vram_size=67108864 \
    -global qxl-vga.romfile=/home/crobinso/src/seabios/out/vgabios.bin
There's also been a report on fedora virt list:


Gerd, any thoughts?

Comment 2 Gerd Hoffmann 2013-07-30 08:17:27 UTC
Doesn't reproduce with the rhel5 guest I have at hand here.  That one is a 32bit install though.  Any chance this reproduces with 64bit only?

Comment 3 Gerd Hoffmann 2013-07-30 10:24:12 UTC
32bit works fine.  64bit breaks.  Both stdvga and qxl, whereas cirrus works fine.

That looks alot like the xorg x86 emulator has problems with seavgabios.
There already some workarounds in seabios (see tools/vgafixup.py), seems
that isn't enougth ...

Comment 4 Gerd Hoffmann 2013-07-31 09:51:48 UTC
Hmm, older x86emu versions don't handle leal properly:


Comment 5 ross tyler 2013-10-10 19:22:54 UTC
Able to reproduce on recently updated fedora 19 installation ...

# versions
rpm -qa | egrep 'qemu|kvm'

# the problem is evident by virtue of failover to text based RHEL installation
# instead of graphical install (due to X failing to start).
# installation will succeed but booted system will also fail to start X

# create a disk image
qemu-img create -f qcow2 -o preallocation=metadata el5.qcow2 8G

# rhel5 fails:
virt-install \
        --name el5 \
        --cpu host \
        --ram 2048 \
        --vcpus 2 \
        --os-type linux \
        --os-variant rhel5 \
        --network network=default,model=virtio \
        --graphics spice \
        --accelerate \
        --cdrom rhel-server-5.8-x86_64-dvd.iso \
        --disk path=el5.qcow2,format=qcow2,cache=none,bus=virtio

# rhel6 succeeds:
virt-install \
        --name el6 \
        --cpu host \
        --ram 2048 \
        --vcpus 2 \
        --os-type linux \
        --os-variant rhel6 \
        --network network=default,model=virtio \
        --graphics spice \
        --accelerate \
        --cdrom rhel-server-6.4-x86_64-dvd.iso \
        --disk path=image.qcow2,format=qcow2,cache=none,bus=virtio

# adding --video cirrus to rhel5 works
# but with poorer graphics than the default --video qlx
virt-install \
        --name el5 \
        --cpu host \
        --ram 2048 \
        --vcpus 2 \
        --os-type linux \
        --os-variant rhel5 \
        --network network=default,model=virtio \
        --graphics spice --video cirrus \
        --accelerate \
        --cdrom rhel-server-5.8-x86_64-dvd.iso \
        --disk path=image.qcow2,format=qcow2,cache=none,bus=virtio

Comment 6 ross tyler 2013-10-10 19:27:17 UTC
should have said (above)

# rhel5 fails:
virt-install \
        --name el5 \
        --cpu host \
        --ram 2048 \
        --vcpus 2 \
        --os-type linux \
        --os-variant rhel5 \
        --network network=default,model=virtio \
        --graphics spice --video cirrus \
        --accelerate \
        --cdrom rhel-server-5.8-x86_64-dvd.iso \
        --disk path=image.qcow2,format=qcow2,cache=none,bus=virtio

Comment 7 ross tyler 2013-10-10 19:28:05 UTC
... and ...

qemu-img create -f qcow2 -o preallocation=metadata image.qcow2 8G

Comment 9 Cole Robinson 2013-10-31 20:19:34 UTC
Solving the root issue here is very tricky. My rough understanding of it is that RHEL5 X server uses some x86 realmode emulator which has bugs handling certain assembly instructions. Some of those bugs are triggered by the assembly that gcc produces for seavgabios. Old vgabios didn't trigger them because it was hand written in assembly (a world nobody wants to go back to). Newer xorg fixed these emulation issues, but old RHEL5 will forever be buggy.

I think it's easier here for people to just do a workaround as ross suggests: if installing a RHEL5 guest, use cirrus graphics. Then when the VM is installed, make sure xorg-x11-drv-qxl is available in the guest, and switch to qxl graphics using virt-manager's UI. That works fine for me.

If the issue is just too difficult to fix in seavgabios, then maybe we can try and work around it in virt-manager/virt-install by using cirrus for RHEL5 guest install, but switch to qxl afterwards. It would need testing though

Comment 10 Dhiru Kholia 2013-11-23 05:37:42 UTC

The idea (switching to QXL after installation) works but the RHEL 5.8 VM stops responding to keyboard and mouse events after a while.

Cirrus graphics sucks (badly) and I can't get a resolution greater than 800*600 with it.

In contrast, VirtualBox and VMware Workstation have absolutely no issues and  they work perfectly well. Time to "borrow" some code?

Comment 12 Fedora End Of Life 2015-01-09 19:03:03 UTC
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Comment 13 Fedora End Of Life 2015-02-17 16:18:22 UTC
Fedora 19 changed to end-of-life (EOL) status on 2015-01-06. Fedora 19 is
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