sanboot and bootsector

[erwan.l]

Hi There,

I have no pb sanbooting a disk image file with a partition boot sector offset = 63 sectors (32256 bytes).
Command is : sanboot --drive 0x80 ${boot-url}/_images/xp.img .

However, when partition offset is 2048 (1048576 bytes), it wont boot. (sanboot error 1d0c6139).
That same image boots fine via other means (iscsi, aoe, boot from disk, etc) so I know the image is fine.

Moreover, when sniffing packets, I notice than ipxe/sanboot first pushes a HTTP HEAD request at 32768 bytes (=64 sectors).
I have the feeling that this is a mistake.
Immediately after, I see another HTTP HEAD at 0 bytes, which I guess is to read the MBR.
And finally right after, I see a HTTP HEAD at 32256 bytes (my partition offset) and then the boot start.

So I have 2 questions :

-is not there a mistake in sanboot+http since first HTTP HEAD goes to 32768?
I would recommend to look by default at 32256.

-is it possible to boot disk images with a partition offset at 1048576 (default with latest windows versions) ?

Note that at this stage, the content of my disk image is not relevant.
It is a plain disk image file with a MBR and one partition with a BS.

Thanks !

Erwan