[syslinux] Is it possible to chainload EXTLINUX from GRUB?

[Gavin D. Smith]

>>Not if the chainloading code is written properly.  Chainloading onto a 
>>logical partition means you have to load not the MBR but the pseudo-MBR 
>>containing the logical partition in question at address 0x600 and point 
>>DS:SI to it.
>>
>>Sounds like a Grub problem to me.
>>
>>       -hpa
>>
> To see if Grub has a problem chainloading onto a logical partition I 
> tried installing GRUB onto the logical partition, and it was successfully 
> loaded. I also tried LILO on the logical partition, and it also was 
> successfully loaded. However trying extlinux I got the same "Boot error" 
> message as before. This may be because of a slight difference in my 
> installing methods that I have overlooked, but I don't know what that 
> might be. I know that the syslinux loader is loaded because "Boot error" 
> is a message in that loader. So you say this message is due to some 
> registers not being set correctly? Would there be a way of seeing what 
> the registers contain so I can tell if they're right or not? I don't have 
> many more ideas of things to try.
>
>Gavin Smith 

Some further points to add to that last post. Trying to load extlinux from 
the MBR supplied with syslinux (cat mbr.bin >/dev/hda), setting the boot 
flag on hda5 failed. However, installing GRUB on the boot record of hda4 
(hda3 is the extended partition) and setting the boot flag on hda4, mbr.bin 
manages to load GRUB. I think this is a lack of functionality in mbr.bin 
(it can't see bootable logical partitions), which may or may not be related 
to the other problems I've been having.

Gavin Smith