viq wrote:
On Thursday 25 May 2006 09:22, Jan Johansson wrote:
akonsu <[EMAIL PROTECTED]> wrote:
dd if=/dev/rwd0c of=mbr count=1
Here is your error
dd if=/dev/rwd0a of=pbr count=1
For the NTLDR you want the PBR (Partition Boot Record) not the
MBR (Master Boot Record). I changed the of= for correct the
terminology the important part is the if= device. I usually use
dd if=/dev/rwd0a of=/mnt/OpenBSD.pbr bs=512 count=1
where /mnt is the mountpoint of a small FAT partiton that is
active.
While at the subject, you need to run this every time you upgrade bootblocks.
What would be the result of not updating bootblocks when upgrading from
snapshot?
"depends".
The boot code doesn't change dramatically often. Last time it happened,
it was the changes that permitted OpenBSD to boot beyond the 8G point on
BIOSs which permitted it. I personally tested around 50 different
machines to make sure it worked, and several hundred other reports were
provided by other users and developers. And when a last minute
improvement was discovered, I had to re-run those tests. :)
So...avoiding updating the boot blocks is usually harmless...you would
be replacing code with the exact same code. Now that I've said that, it
will probably change, and in an important way.
> Or not rerunning that command when updating them?
As indicated by others, the system won't boot.
The inode for the second-stage boot loader (/boot) is hard-coded in the
PBR. Change that inode, you have a problem, because what the NTLDR does
is invoke the PBR that was saved...IN THE PAST. So, that PBR will end
up trying to pull in and run who-knows-what...and will likely fail.
Ugly? Well, before that bootloader change, the actual physical blocks
were coded in the PBR, which meant recopying the file /boot would break
the boot process. The current process is actually very robust,
recopying the /boot file doesn't change the inode number normally. The
normal upgrade processes are done in such a way that the inode isn't
changed, so this will rarely be a problem.
The good news, almost by definition, a multi-booting machine isn't at
some "remote" location...it's in front of you, thus easy to repair.
(yeah, I am sure someone has a weird setup. whatever).
Nick.
