Grub

Tim ignored_mailbox at yahoo.com.au
Sun Aug 19 03:10:05 UTC 2007


On Sun, 2007-08-19 at 01:24 +0000, Marko Vojinovic wrote:
> The only thing that *can* read the disk is the *bios*, and in a very
> clumsy way --- the program that wants the data needs to specify the
> hardware position where the data is written down, and ask the bios to
> instruct the controller to move the heads to the appropriate position
> and read off the data. When grub wants to read its configuration data
> from /etc/grub.conf, that is precisely what it needs to do. ASK THE
> BIOS TO READ IT. And based on that information, a kernel executable
> should be loaded (and executed). The kernel executable is a file 
> called vmlinuz-something, residing in /boot/. So how does grub read
> the kernel file? ASK THE BIOS TO READ IT.
> 
> And now we get to the point. Some bioses do not read past the 1024
> cylinder. If the kernel file is beyond that point, bios fails to read
> it. So grub fails also. And the computer does not boot. 

I was under the impression that the BIOS only needed to be able to
access the first two or three GRUB stage files, and the third one was
used for accessing drives from that point (e.g. loading the kernel),
bypassing the BIOS.

-- 
[tim at bigblack ~]$ uname -ipr
2.6.22.1-41.fc7 i686 i386

Using FC 4, 5, 6 & 7, plus CentOS 5.  Today, it's FC7.

Don't send private replies to my address, the mailbox is ignored.
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