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+--- Thread: sanboot and bootsector (/showthread.php?tid=7053)
sanboot and bootsector - erwan.l - 2013-10-13 11:20
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
RE: sanboot and bootsector - mcb30 - 2013-10-14 15:15
(2013-10-13 11:20)erwan.l Wrote: -is not there a mistake in sanboot+http since first HTTP HEAD goes to 32768?
I would recommend to look by default at 32256.
This isn't a mistake. The code in int13.c will look at offset 32768 for an ISO9660 primary volume descriptor, to find out if the SAN-booted device is a CD-ROM image.
The fact that you see a read from offset 32256 indicates that the MBR code is executing correctly and attempting to read from the correct partition offset.
Quote:-is it possible to boot disk images with a partition offset at 1048576 (default with latest windows versions) ?
Yes, there should be no problem with that.
The error you are experiencing (http://ipxe.org/1d0c6139) indicates that your web server is returning some kind of error status code which iPXE doesn't know how to handle. Could you check your web server logs (or enable DEBUG=httpcore) to find out what status is being returned?
Michael
RE: sanboot and bootsector - erwan.l - 2013-10-14 15:23
Ok got it !
So it first checks offset 32768 for an iso volume descriptor, if not found goes back to offset 0 to read the mbr and from there gathers what ever offset it needs to jump to (usually 32256 or 1048576 for latest windows disks).
I was wondering where the code was : will look at int13.c with interest !
I'll check my web server to check the error codes.
Thanks for your support !