2004-04-18 Yoshinori K. Okuji <okuji@enbug.org>

* docs/grub.texi (Making a GRUB bootable CD-ROM): New section.

	* stage2/disk_io.c (set_device): Use CH instead of *DEVICE to
	test the first character of DEVICE, because DEVICE is
	incremented.
	Reported by Bernhard Treutwein.

ChangeLog

@@ -1,3 +1,12 @@
+2004-04-18  Yoshinori K. Okuji  <okuji@enbug.org>
+
+	* docs/grub.texi (Making a GRUB bootable CD-ROM): New section.
+
+	* stage2/disk_io.c (set_device): Use CH instead of *DEVICE to
+	test the first character of DEVICE, because DEVICE is
+	incremented.
+	Reported by Bernhard Treutwein.
+
 2004-04-15  Yoshinori K. Okuji  <okuji@enbug.org>
 
 	* netboot/fsys_tftp.c (buf_fill): Cast 1 to unsigned short

docs/grub.texi

@@ -485,6 +485,7 @@ directory}, and the directory where the boot loader needs to find them
 * Creating a GRUB boot floppy::
 * Installing GRUB natively::
 * Installing GRUB using grub-install::
+* Making a GRUB bootable CD-ROM::
 @end menu
 
 
@@ -665,6 +666,61 @@ unless you are very familiar with the internals of GRUB. Installing a
 boot loader on a running OS may be extremely dangerous.
 
 
+@node Making a GRUB bootable CD-ROM
+@section Making a GRUB bootable CD-ROM
+
+GRUB supports the @dfn{no emulation mode} in the El Torito
+specification@footnote{El Torito is a specification for bootable CD
+using BIOS functions.}. This means that you can use the whole CD-ROM
+from GRUB and you don't have to make a floppy or hard disk image file.
+
+For booting from a CD-ROM, GRUB uses a special Stage 2 called
+@file{stage2_eltoriro}. All you need to have in your bootable CD-ROM
+are this @file{stage2_eltorito} and optionally a config file
+@file{menu.lst}. You don't need to use @file{stage1} or @file{stage2},
+because El Torito is quite different from the standard boot process.
+
+Here is an example of procedures to make a bootable CD-ROM
+image. First, make a top directory for the bootable image, say,
+@samp{iso}:
+
+@example
+$ @kbd{mkdir iso}
+@end example
+
+Make a directory for GRUB:
+
+@example
+$ @kbd{mkdir -p iso/boot/grub}
+@end example
+
+Copy the file @file{stage2_eltorito}:
+
+@example
+$ @kbd{cp /usr/share/grub/i386-pc/stage2_eltorito iso/boot/grub}
+@end example
+
+Then, make the config file @file{menu.lst} under @file{iso/boot/grub}
+(@pxref{Configuration}), and copy files and directories to the
+directory @file{iso} as you wish.
+
+Finally, make a ISO9660 image file like this:
+
+@example
+$ @kbd{mkisofs -R -b boot/grub/stage2_eltorito -no-emul-boot \
+    -boot-load-size 1 -boot-info-table -o grub.iso iso}
+@end example
+
+This produces a file named @file{grub.iso}, which then can be burned
+into a CD (or a DVD).
+
+Note that you can use the device @samp{(cd)} to access a CD-ROM in your
+config file. But you won't have to use this feature, because GRUB
+automatically sets the root device to @samp{(cd)} when booted from a
+CD-ROM. So it is not necessary to specify the device name explicitly,
+unless you want to access other drives as well.
+
+
 @node Booting
 @chapter Booting
 
@@ -1504,8 +1560,9 @@ different passwords for different entries.
 @chapter GRUB image files
 
 GRUB consists of several images: two essential stages, optional stages
-called @dfn{Stage 1.5}, and two network boot images. Here is a short
-overview of them. @xref{Internals}, for more details.
+called @dfn{Stage 1.5}, one image for bootable CD-ROM, and two network
+boot images. Here is a short overview of them. @xref{Internals}, for
+more details.
 
 @table @file
 @item stage1
@@ -1544,6 +1601,11 @@ While Stage 2 cannot generally be embedded in a fixed area as the size
 is so large, Stage 1.5 can be installed into the area right after an MBR,
 or the boot loader area of a ReiserFS or a FFS.
 
+@item stage2_eltorito
+This is a boot image for CD-ROMs using the @dfn{no emulation mode} in
+El Torito specification. This is identical to Stage 2, except that
+this boots up without Stage 1 and sets up a special drive @samp{(cd)}.
+
 @item nbgrub
 This is a network boot image for the Network Image Proposal used by some
 network boot loaders, such as Etherboot. This is mostly the same as
@@ -1617,6 +1679,9 @@ If you enabled the network support, the special drive, @samp{(nd)}, is
 also available. Before using the network drive, you must initialize the
 network. @xref{Network}, for more information.
 
+If you boot GRUB from a CD-ROM, @samp{(cd)} is available. @xref{Making
+a GRUB bootable CD-ROM}, for details.
+
 
 @node File name syntax
 @section How to specify files

stage2/disk_io.c

@@ -1011,7 +1011,7 @@ set_device (char *device)
 	  else
 #endif /* SUPPORT_NETBOOT */
 	    {
-	      if (*device == 'c' && cdrom_drive != GRUB_INVALID_DRIVE)
+	      if (ch == 'c' && cdrom_drive != GRUB_INVALID_DRIVE)
 		current_drive = cdrom_drive;
 	      else
 		{