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KVM-77 Released: -std-vga deprecated, Improved disk performance

Monday, October 13, 2008 - 10:16 Haydn Solomon

Yesterday kvm maintainers released kvm-77 which includes a fix for the –std-vga regression described here after the last release.

Also included in this release are performance improvement for disk and a new syntax for vga options pulled from upstream qemu. The previous syntax of –std-vga has been deprecated for a new –vga option. Below is an excerpt from documentation describing the new change.

 

 

New vga option

Instead of having three command line switches ie -std-vga, -cirrusvga and -vmwarevga, you now provide one -vga switch which takes an argument, so that:

  • qemu -std-vga becomes qemu -vga std
  • qemu -cirrusvga becomes qemu -vga cirrus
  • qemu -vmwarevga becomes qemu -vga vmware

 

Changelog

The official changelog for kvm-77 released is as follows:

Changes from kvm-76:

- merge bochs-bios-cvs
- merge qemu-svn
- more -cpu options
- faster disk emulation (esp. with scsi/virtio)
- improved NMI support (Jan Kiszka)
- improve >4GB memory support (Alex Williamson)
- memory alias cleanups (Glauber Costa)
- fix kvmtrace segfault (Ryota OZAKI)
- make external module compile on split source/object configs (Alexander Graf)
- allows compiling on opensuse
- fix -std-vga regression
- fix migration failure at end of migration protocol
- map mmio pages for device assignment (Weidong Han)
- silence lapic kernel messages (Jan Kiszka)
- fix vcpu reset (Gleb Natapov)
- fix missed invlpg on EPT-enabled machines with EPT disabled (Marcelo Tosatti)
- device assignment on ia64 (Xiantao Zhang)
- memory type support on EPT (Sheng Yang)

KVM-77 can be downloaded here
 

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Comments

Which one?

Monday, October 13, 2008 - 13:05 falstaff2 (not verified)

This VGA changes leads me to a question: Which VGA driver do you use for Linux virtualization? At the moment I use what virt-manager uses as standard, but I would like to have a bigger resultion, so which one should I choose? Does any of this drivers support a higher resolution (than 1024x768, which I use atm)...

Thanks
bye
falstaff

Re: Linux VGA

Monday, October 13, 2008 - 13:44 Haydn Solomon

The best option for Linux guest is -vga std. However you will also need to configure your linux guest to then use cirrus vga driver. The max resolution you can get with this setup will probably be about 1400x1050 due to limitations of the linux cirrus driver.

This is the best I've been able to achieve after researching this and will be happy to hear if anyone has gotten any better resolution on a linux guest.

Re: Linux VGA

Tuesday, October 14, 2008 - 03:33 slubman

Strange you can't get better than 1400x1050.

Using the -std-vga (or -vga std now), and the vesa driver, I can get 1680x1050 and even 1920x1200 of my Linux guests. I've to force the reolution in xorg.conf, but it really works.

Windows also can achieve the 1680x1050 resolution (I've not yet tested 1920x1200).

Slubman, I can actually get

Tuesday, October 14, 2008 - 10:01 Haydn Solomon

Slubman, I can actually get around the 1600x1200 after having another look at it but that resolution doesn't fit my screen very well cause of the height. Nevertheless, I haven't been able to get the 1920x1200 to work. What changes did you make to your xorg.conf to achieve this? Also what distribution are you using?

My settings

Tuesday, October 14, 2008 - 12:16 slubman

Guest : ArchLinux, running kernel 2.6.27, kvm-77

Hosts :

  • Fedora 9 : using 2.6.26, vesa driver (full xorg config), paravirtualized NIC, and Hard-Drive.
  • Windows : paravirtualized NIC

Those two guests can achieve 1920x1200 resolution using -vga std.

Also, I'm using them through VNC if it can change something.

It works!

Wednesday, October 15, 2008 - 02:24 falstaff

Thanks for your answers, it works now with higher resultion! Im using -std-vga and vesa driver. The vesa driver was not installed (Im using Ubuntu). I've documented it here, but in german :-)

What is the highest

Wednesday, October 15, 2008 - 08:36 Haydn Solomon

What is the highest resolution you can get falstaff?

LVM Issues

Wednesday, October 15, 2008 - 10:49 FredR

I had a Fedora 9 image which worked well under kvm-75 but an update to kvm-77 broke it.

It finds the LVM group, but then init complains about unterminated blocks and unknown stanzas in /etc/event.d/{sulogin|tty?} ...

See a screenshot here.

Host machine is Slamd64 (64bit port of slackware), and using buildscript from Slackbuilds.org.