Re: [Qemu-devel] using partition images

[Jim C. Brown]

On Mon, May 08, 2006 at 03:28:31PM +0100, Paul Brook wrote:
> > If split vmdks are just a series of partition images plus an image of an
> > MBR/partition table then it may be possible to hack this up via a partition
> > driver that supported harddisk sharing (using multiple partition images as
> > part of the same hard disk).
> 
> I think you should be aiming for a generic composite device block driver.
> Then write a fake MBR block device (or whatever you want to call it).
> 
> To use a single partition you create a composite device consisting of the 
> fake 
> mbr and the raw partition.

I'm not sure if it's worth it to make the fake MBR its own block device.

Since we're going to need configurable options anyways, it might be possible
to specify how the MBR should be handled. E.g.

-hda 
multipart:mbr:fake:part1:/usr/images/hda1.img:part1sysid:0xc:part2:fat:floppy:/usr/images/tools:part2sysid:0x6

would handle the current faking of the mbr using bootmbr.bin and autogenerated
partition table, while

-hda 
multipart:mbr:file:/usr/images/vmdk-mbr.vmdk:part1:/usr/images/hda1.vmdk:part2:/usr/images/hda2.vmdk

would allow for having the mbr as a separate file. And even

-hda multipart:mbr:part1:part1:/usr/images/hda1.vmdk:part2:/usr/images/hda2.vmdk

which would specify that hda1.vmdk has the mbr and partition table prepended to 
it.

The syntax is getting kinda ugly though. Anthony suggested that we use 
mini-config
files with all the options and just pass those to -hda (e.g. -hda 
multipart:hda.config)

> 
> A vmware split image file is just a composite of several raw images with a 
> funny config file.

It'd still be nice if the vmware driver had support for using those config files
instead of requiring a user to type this out by hand.

I guess qemu-img could have an option to convert those config files into qemu
multipart/composite harddisk image configs.

> 
> Paul
> 

-- 
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Infinite precision begets infinite perfection.