[syslinux] Knowing your boot disk

[H. Peter Anvin]

Ram Yalamanchili wrote:
> folks,
> 
> If you boot from syslinux based USB/harddisk, is there a way to know the
> partition or disk you booted from? I'm using the mboot module, so if the
> info is availble to thru the COM api, i can get it and append it to cmdline.
> 

Sort-of kind-of.

The BIOS disk number and partition information are available to COM32 
via INT 22h, AX=000Ah, but the question is exactly how much that would 
buy you, since the mapping between BIOS disk numbers and Linux device 
names isn't really all that well-defined.

It's probably more useful for EXTLINUX where you, with that information, 
could go in and read the UUID from the filesystem superblock -- I 
probably should add an API function to read partition-relative disk 
blocks rather than relying on each COM32 program to deal with all the 
rigamarole of EBIOS, CBIOS, partition layout, etc, itself.

	-hpa