[Qemu-devel] Re: RE : Re: Re: NBD server for QEMU images

[Salvador Fandino]

Jim C. Brown wrote:
> On Wed, Dec 13, 2006 at 08:03:13PM +0100, Salvador Fandino wrote:
>>> The code of lomount might be what you're looking for. Lomount allows one
>>> to mount partions (via loop) from a raw diskimage.
>> That was my intention, but I have found that lomount handling of EBR and
>> logical partition is not correct, they perform as if EBR where
>> structured as MBR, what is wrong!
>>
>> Cheers,
>>
>>   - Salva
>>
> 
> How is it incorrect? What needs to be fixed?
> 
> My understanding is that the extended partition has a partition table
> set up with the first partition entry pointing to the logical partition,
> the second entry pointing to a partition table that exists immediately
> after the logical partition, and then the 3rd and 4th entries are not
> used. The second partition table is structed the same way, so you
> essentially have a linked list of extended partitions. (Unlike the MBR,
> there are no boot sectors associated with these partition tables.)
> 

yes, that's right, but it's not what lomount does. It parses the data on
the EBR in the same way as the MBR, reading 4 partition registers from them.

EBRs are explained here: http://en.wikipedia.org/wiki/Extended_Boot_Record

I believe that the implementation in the last version of qemu-nbds I
have uploaded to the forum is correct.

Cheers,

  - Salva