El Torito suppor is added

[Yoshinori K. Okuji]

Hello all,

I have added support for El Torito with no emulation mode into the CVS 
right now. The patch is originally written by Leonid Lisovskiy, and I 
myself modified his patch and added some features.

Here is his comments on the original patch:

> Below is very short documentation for this patch.
> 
> This patch add capability of recognizing/reading ISO9660+RockRidge 
filesystem
> to Grub and has following limitations:
> 
> 1) It cannot process multisession CD (recognizes only first session),
>  but bootable CD cannot be multisession.
> 
> 2) It cannot mount CD if it is not attached to system by BIOS
> previously ( i.e. CD-drive mapped by BIOS itself to (hdxx) ) - because 
most of
> BIOS'es has broken capability turning on El'Torito emulation by BIOS 
INT
> 13h AX=4A00h call.
> 
> 3) It don't support RockRidge symlinks yet.
> 
> 4) It don't add special device name of CD-ROM to Grub, e.g. (cd0) -
> usually BIOS maps CD-ROM to (hd31) or number_of_last_real_hdd+1
> 
> 
> Example how to make a bootable CD with Grub:
> 
> mkisofs -R -b boot/grub/stage2_eltorito -no-emul-boot -boot-load-size 
1
> -boot-info-table  <root-of-iso-tree>
> 
> You have to omit device name from Grub boot menu file (menu.lst) to
> force substitution of boot device name, it will be determined
> automatically by Grub during stage1 load.

But I have added a new drive name (cd) for a CDROM drive. This is 
assigned only if you boot GRUB from a CDROM drive. So you can specify 
(cd) in your config file or in the command-line interface, if you wish.

For now, I haven't added information about this into the manual yet. I 
hope someone will contribute to this task.

Since this patch has changed some critical parts substantially, I'd like 
many people to test the CVS version, in particular if can test a 
bootable CDROM. Please report your result to this list, whether it is 
successful or not. If you don't know how to get the CVS version, take a 
look at the GRUB web site.

Cheers,
Okuji