[Qemu-devel] harddrives and QEMU

["Brett (Mare) Henley" <mare@shires.org>]

Hello all,
   Been a long time user and appreciator of QEMU and would like to thank 
everyone who put so much hard work into it.
   I found a difficulty that I'm not sure where to start so this could be
a lengthy email.
   The short of it goes like this:
    I hook up a 12G IDE drive through a usb-ide adaptor so I can boot 
off it using qemu with Windows as the Host OS. On the drive is FreeBSD. 
I can boot off this drive with my machine just fine and I realized it 
would be a boon if I could use my usb adaptor to build or update new 
boot drives etc.
    WaxDragon was savvy enough to tell me to access a drive like this in 
windows I need to use -hda \\.\PhysicalDriveX (where X is a drive number 
  that the storage manager thinks should be it usually 1)
    To my joy FreeBSD actually started to boot. I was amazed and then it 
got to sizing up my drive (Mind you the Bios reported a drive size of -1 
Mbytes) It hung for a long time. Started chewing up memory and every 10 
seconds or so the drive would access and rattle. Finally a report of the 
drive size came that said something like 248043832 Megabytes. And my 
windows machine got slower and slower it took 5 minutes to get the qemu 
console up and another 5 before my quit command took effect.
   That's the short synopsis.
   The Longer one goes into greater detail. WaxDragon's first suggestion 
was to use -hdachs to define the drive for the bios. I had to read up 
well to do this but entered 65383,16,63 as my definition and still ended 
up with exactly the same behavior.
   Still determined to make something of this. I tried a 4G HD and by 
using -hdachs 8912,15,63 (from reading it on the drive) I got a 
respectable though not entirely accurate bios size and the machine in 
qemu booted puppy linux and let me install it on the hard drive. 
Ultimately using this method I had a pack I could boot off of using a 
line like:
  qemu -L . -m 192 -hda \\.\PhysicalDrive1 -localtime -enable-audio

   I didn't need the -hdachs and it booted spiffy as can be. Trying
to get it to boot off a real machine was a good bit more problematic as 
the drive would be lettered /dev/sda1 etc so grub had a fit and needed 
to be told otherwise. Still when all the kinks were worked around it 
actually booted and worked. But not nearly as easy as it could have.
   Thinking perhaps it's a question of an 8G limit I tried a 6G drive 
via usb and had the same trouble sizing and using the drive I did with 
the 12G drive.
   I also understand there's a problem with Linux QEMU accessing large 
drives via device node.
   Is there any work being done to fix or create options to make using 
physical drives as easy as using image files?
   Is there any work being done to let physical drives be considered
another type of drive. Such as a usb drive instead of a ide drive. This 
would help making os installation much simpler on hard drives from the 
host OS.

Thanks.