Re: [Qemu-devel] QEMU with KNOPPIX

[Kuniyasu Suzaki]

 >>From: "John R. Hogerhuis" <address@hidden>
 >>Subject: Re: [Qemu-devel] QEMU with KNOPPIX
 >>
 >>On Thu, 2004-08-26 at 00:57, Kuniyasu Suzaki wrote:
 >>
 >>> But I think the option is not valuable on QEMU. It makes slow boot on QEMU.
 >>> To make short-cut of boot is most important.
 >>
 >>How long does it take to transfer the CLOOP file to hard disk?
 >>
 >>I would think that you could do it just once, say and drop it in My
 >>Documents, or wherever the user wants, with a pointer to the file in the
 >>registry. Don't have the virtual machine do it (that's slow), have the
 >>script that starts QEMU copy the file to the host's hard disk before
 >>running QEMU. Also put a version number there. Then read some version

Excuse me. My explanation looks bad. KNOPPIX on QEMU/Windows boot with
iso image. QEMU cann't boot KNOPPIX from CLOOP directly.

The current version of "KNOPPIX on QEMU/Windows" is not smart. 
  >qemu.exe -L . -m 128 -boot a -fda qemu-boot.img -hda \\.\d -hdachs 
1407,16,63 -user-net -enable-audio -localtime

The bad points are following.
 1. We have to prepare DF boot image "qemu-boot.img".
 2. The current QEMU/Windows can to use "-cdrom \\.\d" option.
    We have to use "-hda \\.\d-hdachs 1407,16,63" option.

The desirable option is the following.
  >qemu.exe -L . -m 128 -boot d -cdrom \\.\d -user-net -enable-audio -localtime

One key point of KNOPPIX with QEMU/Windows is that it boots form
CD-ROM. It does not require hard disk.

Anyway I want to speed up the boot time. The short-cut by taking
snapshot-of-boot makes it possible.

 >>number off the Knoppix disk... if they match, and the file is already on
 >>the hard drive don't copy it again. So you get a one-time hit, for
 >>hopefully a big performance gain and the user won't see it again until a
 >>new version of knoppix-qemu-win comes out (BTW, what is a good name for
 >>this? kqw? something short... I actually registered a domain when I
 >>thought of this possibility sometime back, "linsitu" if that makes any
 >>sense to anyone...)
 >>
 >>Might be a cool, general way to do this transparently in QEMU. What if
 >>there was a option/feature in QEMU, that as it reads from a CD-ROM, it
 >>builds a cache of it on the hard disk. Maybe it saves some unique info
 >>from cd, and the hash for some random blocks. Then when QEMU is started
 >>again with the same disk, it hashes those blocks and decides whether it
 >>already has cached any/all of that cd on hard disk. If it has it reads
 >>from cache of that cd on hard disk. Then you would have something that
 >>could work with any bootable linux cd without any tweaking.
 >>
 >>But booting a suspended image will probably save a lot of time so either
 >>one is worth some focus.
 >>
 >>I don't think the QEMU engine itself is off the hook either. There are
 >>definitely things that could be squeezed there, the question is, is
 >>there any low-hanging fruit which would provide a measurable performance
 >>gain...
 >>
 >>-- John.

------
suzaki