Re: Make grub treat a virtual hard disk as a physical hard disk

[Vladimir 'φ-coder/phcoder' Serbinenko]

On 15.04.2011 21:41, Lennart Sorensen wrote:
> On Fri, Apr 15, 2011 at 03:37:32PM -0400, Swapnesh Chaubal wrote:
>> I am working on booting a physical machine using VHD files (regarding which
>> I have not accomplished much) and I believe one way to go about it would be
>> to make grub treat a virtual hard disk as physical hard disk. This way, the
>> physical machine does not need to know what it is booting from and the rest
>> of the booting and running should proceed as it normally does.
>>
>> Is there any way to achieve this?
> And who is going to map the VHD file to the physical disk for the system
> running from the VHD file?
>
> You probably could convince grub to read a filesystem, find a vhd file,
> teach grub how to parse it and figure out how to find the right offsets
> in it to read its filesystem and find the kernel to boot that way,
This part is done and supported (loopback command) as long as the disk
format is raw (I don't know whether VHD is raw or not).
>  but
> you still have the larger problem of then making that kernel work with
> a VHD file rather than direct hardware access (in fact it would have to
> do both.  Read the physical device and filesystem to get at the vhd and
> read that).
This part is OS-specific. In case of GNU/Linux, FreeBSD, GNU/kFreeBSD,
NetBSD, OpenBSD, xnu-based Systems (Darwin and MacOSX), Solaris and
probably some other multiboot systems you can have a small initial
ramdisk which is used as root at first and has a sole purpose of finding
the other root and mounting it accordingly.

-- 
Regards
Vladimir 'φ-coder/phcoder' Serbinenko

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