[syslinux] chainboot from grub to syslinux in logical partition

[Cynthia Flynn]

On Thu Feb 26 15:21:51 PST 2009, Jeff Sadowski wrote:
>> This is a windows limitation you can not as far as I know mount them
>> as their own drive letters in windows.
>> If it has a drive letter you can use syslinux on it. I'll experiment
>> more with windows and the disk management in it to try and find a way
>> around this but it seems like a windows limitation. I'll try vista
>> when I get a chance also.
> 
> http://www.lancelhoff.com/make-windows-see-any-usb-flash-drive-as-local-disk/
> here is how to get the second partition to be seen by windows xp then
> you can use syslinux on it as normal.

Yes, I was well aware of the Windows XP limitation and the possible 
modification, which is why I said "not normally possible". However, we 
need a solution that does not require this non-standard configuration of 
Windows XP. Vista is of no interest to us.

On Thu Feb 26 03:48:10 PST 2009, Ferenc Wagner wrote:
>> My thinking is that this would be possible if I could get syslinux
>> or some other utility to write a proper volume boot record to the
>> logical partition's boot sector without altering the thumb drive's
>> master boot record.
> 
> This is exactly what the syslinux installer does under Linux.  Are you
> sure it's different under Windows?  (Warning: I never used syslinux
> under Windows.  I havn't been using Windows for several years.  I've
> never used syslinux to boot from a logical partition.)

Again, the procedure cannot work under in an unmodified Windows XP 
environment. However, I did follow your Linux lead, Ferenc. Since one of 
the thumb drive's partitions contains a working live Linux-based file 
system, I booted that and used the Linux syslinux binary it contained to 
install the boot sector and ldlinux.sys into the logical partition of 
interest. I confirmed that the boot sector actually had been modified 
and that ldlinux.sys appeared in that partition's root. I then added the 
appropriate entry in my grub configuration file to chainload that 
logical partition. Unfortunately, all I got when trying to boot that 
logical partition was the infamous and uninformative "Boot error" 
message. I believe that comes from syslinux, which would mean that 
control is indeed being passed from grub to the syslinux boot sector I 
installed. Beyond that I've no idea what's happening. The target 
partition has it's own syslinux directory containing it's own 
configuration menu files which I would expect to be read and acted upon, 
but I imagine things aren't getting far enough for that. FWIW, I'm using 
syslinux v3.73 when I install it to the logical partition and two of the 
logical partitions I'm experimenting with contain Trinity Rescue Kit 3.3 
and the Ultimate Boot CD 4.1.1. Both are FAT16 and both give me the 
"Boot error" message.

So, is there some fundamental reason why grub should not be able to 
chainload a logical partition with a proper syslinux VBR and ldlinux.sys 
or am I still missing something in my procedure? Perhaps syslinux does 
not in fact write a proper VBR in a logical partition?

Cynthia