Message-ID: <1847.192.168.201.6.1127236405.squirrel@pc300>
Date: Tue, 20 Sep 2005 18:13:25 +0100 (BST)
From: "Etienne Lorrain" <etienne.lorrain@masroudeau.com>
To: linux-kernel@vger.kernel.org
Reply-To: etienne.lorrain@masroudeau.com
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Subject: Re: [i386 BOOT CODE] kernel bootable again
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>>>> So if the "something" knows (or can get to know) the sector/tracks
>>>> layout of the disk it's writing the kernel onto, it could store this
>>>> information in the bootblock (is there space for that?). The bootblock
>>>> code would then just read this info and use it.
>
> Actually, DOS/Windows works that way. FAT filesystem stores the number
> of sectors per track in its boot sector.

  Gujin installer creates the filesystem (and the partition table if
 needed), the MBR with the disk geometry, and chain a simple bootloader
 or a menu based bootloader on the created FAT filesystem when told to
 do so.

  So if you just want to put a kernel and initrd on a floppy, and the
 floppy is big enough, you just do:
$ mkdir tmp
$ cd tmp
$ wget http://heanet.dl.sourceforge.net/sourceforge/gujin/install-1.2.tar.gz
$ tar xvzf install-1.2.tar.gz
$ ./instboot tiny.bin /dev/fd0
$ mcopy /boot/vmlinuz-2.6.13 a:
$ mcopy /boot/initrd-2.6.13 a:
  And you reboot with the floppy still inside the drive.

  If you want to put them on your USB thumb drive, and your PC can
 boot USB flash drives as a floppy (lot of BIOS bugs there), you
 just change the line (double check that your USB key is /dev/sda):
$ ./instboot tiny.bin /dev/fd0
  by:
$ ./instboot tiny.bin /dev/sda --disk=BIOS:0x00 --geometry=/dev/sda

  I personnally better like a partition table on my USB drives, so
 I am more used to erase manually the partition table:
$ dd if=/dev/null of=/dev/sda bs=512 count=64 # blank the head of the disk
 and then type:
$ ./instboot boot.bin /dev/sda --disk=BIOS:0x00 --geometry=/dev/sda \
     --mbr-device=/dev/sda --partition_index=1

  When booted from this key, the PC will boot the kernel named vmlinuz*
 and load the initrd/initramfs named initrd* (tiny.bin does not contain
 the graphic menu management).

  I will not say that I tested it lately, but you may also want to put
 your kernel and initrd on a bootable CDROM - without having the usual
 Gujin menu - then you just do:
$ mkdir tmpdir
$ cp /boot/vmlinuz-2.6.13 tmpdir
$ cp /boot/initrd-2.6.13 tmpdir
$ ./instboot tiny.bin tmpdir/tiny.bcd
$ mkisofs -untranslated-filenames -no-emul-boot -boot-load-size 4 \
    -b tiny.bcd tmpdir -o boot.iso
$ cdrecord boot.iso

  It is usually better (and will work for all those configuration)
 to put the kernel and its initrd inside a directory named "/boot",
 but I am highjicking a thread so want to keep it simple...

  Etienne.

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