[Qemu-devel] Re: [PATCH] Snapshot block device support

[Rusty Russell]

In message <address@hidden> you write:
> I had plans to implement "copy on write" disk images...I find your 
> approach original. My initial plan was just to add a second disk image 
> for each disk containing the changes. It should be easy to do it from 
> your code (for example by adding options '-hdacow file' where file is 
> the snapshot file you use).

Sure: I used a temporary (unlinked) file because I couldn't see much
point in keeping it around.  Since most filesystems do sparse files,
it's quite efficient, too.

-hdacow with an optional argument would work really well, if that's
 desired behaviour.

I'm glad I finally beat you to implementing something: you're usually
too quick 8)

> About IDE, it is working (at least with kernel 2.4.20). Someone has even 
> compiled a linux kernel inside QEMU (slowdown factor of about 15), so vl 
> begins to be usable for real tasks. There are still known problems if 
> several processes use floating point at the same time.

OK, I'm getting errors with IDE on 2.5, but shouldn't be too hard to
track down.

Thanks!
Rusty.
--
  Anyone who quotes me in their sig is an idiot. -- Rusty Russell.