On Thu, 2008-06-05 at 01:35 +0200, Robert Millan wrote: > It seems that open_device() in biosdisk is messing up offsets when > accessing partitions. For example if you try: > > grub> hexdump (hd0,1) > > in grub-emu, you'll get a message saying lseek failed. The problem is that > it substracts to the sector offset, so all accesses get to wrong data and > accessing sector 0 results in underflow. > > I would think those lines (see patch) are plainly wrong, but they appear to > be very old, and it is strange that this wasn't noticed earlier. Maybe we > have changed behaviour around partition/disk offsets, causing this breakage > without noticing?
The question whether sector is relative to the partition or to the whole disk. From what I see in disk/memdisk.c or it disk/i386/pc/biosdisk.c, the sector is relative to the whole disk. There is no compensation for partition offsets. That's low-level code that doesn't know about partitions, and util/biosdisk.c correctly tries to emulate that. I guess grub-emu gets it wrong somewhere. -- Regards, Pavel Roskin _______________________________________________ Grub-devel mailing list Grub-devel@gnu.org http://lists.gnu.org/mailman/listinfo/grub-devel
