[Barrelfish-users] GRUB really slow in qemu-kvm

Georgios Varisteas yorgos at kth.se
Tue Jul 17 16:17:21 CEST 2012

Hi Zeus,

Do you know if Qemu can use a physical partition?

It's doable in VMware and VirtualBox by creating a special vmdx file that actually maps to specific physical partitions. The setup I've found most helpful is to use a floppy img with GRUB, to include a config from the physical partition. That way it's ultra fast to push changes in my code plus all the speed benefits of a physical disk.

Unfortunately VirtualBox stopped working after the latest update and I've had no time to investigate why.


From: zeus at aluzina.org [zeus at aluzina.org] on behalf of Zeus Gómez Marmolejo [zeus.gomez at bsc.es]
Sent: Tuesday, July 17, 2012 15:17
To: Georgios Varisteas
Cc: barrelfish-users at lists.inf.ethz.ch
Subject: Re: [Barrelfish-users] GRUB really slow in qemu-kvm

Yes, I've been experiencing this problem for long time.

The only thing I can say that it's related to the TFTP emulation that QEMU is doing. If you load the modules from a virtual hard drive, it's booting much faster.

It would be great to solve this issue by either submitting a patch to QEMU or changing the boot media on GRUB.


2012/7/17 Georgios Varisteas <yorgos at kth.se<mailto:yorgos at kth.se>>

I recently tried running BF under qemu with kvm-intel. It runs 10x faster than without kvm. However GRUB is a lot slower in loading the modules which in overall means no actual gain. Any hints on why is that and maybe how to solve it?


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Zeus Gómez Marmolejo
Barcelona Supercomputing Center
PhD student

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