[Qemu-devel] Re: What is the minimal linux setup for running Qemu ?

[Ronald <look@reply.to>]

Le Thu, 23 Dec 2004 01:40:57 +0000, Richard Neill a écrit :


> Exactly. And as you say, the problem is that writing to files in a virtual
> disk means that any slight corruption to the real physical file may
> completely destroy the filesystem on the virtual disk. A crash of the host
> would also be less damaging.
> 
> What *would* be cute would be to use the virtual vfat driver. Thus files
> on the guest map to real files on the memory key. If you do this, the
> number of writes will be exactly the same as if you used the memory key
> for transport of files in the usual way.
> 
> 
> My ideal set up would be the following:
> 
> 
> USB-memory-key/
> 		/qemu/mac   <-  mac binaries for qemu and bios /qemu/linux <- linux
> 		binaries for qemu and bios /qemu/win   <-  windows binaries for qemu and
> 		bios
> 
> 		/dsl/iso    <-  dsl iso itself
> 		/dsl/extras <-  extra apps for dsl if desired.
> 
> 		/myfiles   <- an ordinary directory, not a disk image.
> 			      appearing to the guest as a drive using
>                                virtual vfat
> 
> 		/putty	   <-  ssh binaries for win,linux,mac /vnc       <-  vnc viewer
> 		binaries for win,linux,mac
> 
> 		win-startup.bat	 <- start up scripts for qemu/dsl mac-startup.sh
> 		linux-startup.sh
> 
> 
> The only problems that remain are:
> 	-  vfat doesn't support Linux file attributes.
>              (there is a solution, but I forget what).
> 
> 	- you need a script to manually save those files within /home
>            that you want to keep. Most can vanish with the ramdisk on
>           reboot, but things like ~/.ssh  and ~/.mozilla are useful!
> 	[DSL and Knoppix both solve this problem somehow ]
> 
> 
> In addition, with the falling prices of memory keys, an entire knoppix iso
> could be used, if desired. Furthermore, since we know exactly what the
> emulated hardware will be, knoppix could be compiled with the appropriate
> optimisations.
> 

I find this set up a bit complicated (or I have not understood the goal
maybe), I think you can do something simpler by using qemu's features like
snapshot and compressed qcow image, this way you only write to the usb
stick if you have done some real changes by commiting to the image.