svn commit: r197608 - head/sys/geom/part

[John Baldwin]

On Monday 28 September 2009 7:52:47 pm Marcel Moolenaar wrote:
> Author: marcel
> Date: Mon Sep 28 23:52:47 2009
> New Revision: 197608
> URL: http://svn.freebsd.org/changeset/base/197608
> 
> Log:
>   The first 96 bytes may not be zeroes. It can contain trivial boot
>   code that merely emits an error and waits for a key press before
>   rebooting. The error being that extended partitions are not
>   bootable. The origin is presumed to be Windows 2000; Windows XP
>   does not do this...
>   
>   For now, ignore the first 96 bytes when checking that the EBR is
>   (for the most part) all zeroes.
>   
>   Tested by:	Mario Lobo <mlobo at digiart.art.br>
>   MFC after:	1 week
> 
> Modified:
>   head/sys/geom/part/g_part_ebr.c

Why do you check for zeros at all?  AFAIK, the only real check is for AA55 at 
the end of the sector (and having an MBR or other Extended MBR partition 
entry point at the sector in question).  The '96' thing seems rather 
arbitrary in the code, and I think the zero's check is overly restrictive.

-- 
John Baldwin