Re: installboot: Old BPB too big, use -f (may invalidate file system)

[Andrew Cagney <andrew.cagney%gmail.com@localhost>]

It probably wasn't clear from my e-mail - I'm using sysinst so I was
expecting things to to go smoothly

On 21 January 2015 at 15:22, Michael van Elst <mlelstv%serpens.de@localhost> wrote:
> andrew.cagney%gmail.com@localhost (Andrew Cagney) writes:
>
>>While trying to squeeze a NetBSD-7 snapshot into a newly created
>>partition on a disk that already contains several other OSs, things
>>died with:
>
>>  installboot -o console=pc,speed=9600 /dev/rwd0a /usr/mdec/bootxx_ffsv2
>>  Old BPB too bug, use -f (may invalidate file system)
>
>
> This says that while installing a boot block, a (somewhat) valid
> BIOS Parameter Block in that location was detected that cannot
> be preserved because it is too large (the BPB is variably sized).
> It is necessary to preserve a BPB in case the partition contains
> a FAT or NTFS filesystem.

Thanks for the explanation.

From memory and guessing, the area covered by the start of partition 3
(where I'm putting NetBSD) has contained:
- random disk data
- netbsd
- an extended partition table (from memory that appears at the start
of a primary partition)
so perhaps in the distant past.

> Unfortunately installboot cannot determine wether the BPB is really
> needed or if the partition is or will be reformatted with something
> (like FFS or ext3) that doesn't require it. Thus the warning.

Ah, but the installer does know this.  in fact I believe it:
- first formatted wd0a with ffsv2
- then tried to do the installboot on wd0a and failed
so if wd0a was set up wrong I'm already be deep in goop.

> You didn't say where wd0a is located, a wrong disklabel might cause
> it to overlap some of your NTFS partitions. But if you are sure that
> you don't accidentally overwrite some innocent valid bootblock, then
> using installboot -f to clean the old BPB is the right thing to do.

I thought I mentioned that.  gparted created the primary partition,
and sysinst set up the NetBSD partitioning (wd0a, wd0b) within that.
I'm pretty sure that gparted and sysinst did things right.

Sounds like two bugs:
- the installer (installboot) getting confused by crud at the start of
a valid wd0a
- (as I mentioned) the installer crashing when told to not run installboot

Andrew