[syslinux] MEMDISK El Torito Emulation

[H. Peter Anvin]

On 11/23/2009 12:05 PM, Shao Miller wrote:
> I wrote:
>> LDLINUX.SYS would be along the same lines as ISOLINUX.BIN.  It's a 
>> simple load-and-jump, so UPX would have to decompress, shuffle, then jump.
> In fact, for LDLINUX.SYS, only the first 512 bytes is loaded by an MBR, 
> then those 512 bytes contain _just_enough_ code to load the rest of 
> LDLINUX.SYS from a known location on the disk.  It would really be quite 
> a feat if UPX could compress these 512 bytes, as well as decompression 
> code and code to shuffle the decompressed 512 bytes back to where they 
> belong, and fit all that in 512 bytes!
> 
> - Shao Miller

For what it's worth, Syslinux 4.00+ is self-decompressing.  It doesn't
use UPX, but it uses the LZO algorithm which is often used by UPX.  The
main reason for using LZO is that the decompressor is *tiny*.

	-hpa