Subject: Re: biosboot.sym & mbr
To: suxm <>
From: Manuel Bouyer <>
List: port-i386
Date: 05/31/2001 20:21:46
On Thu, May 31, 2001 at 08:49:47AM +0800, suxm wrote:
> Hello,
> Would someone like to tell me the relationships between biosboot.sym and mbr ?
> The 'man installboot' said :
> ------------------------------------------------------------------------------------
>     The NetBSD/i386 disk bootstrap software is split into two parts: a small
>      first-stage boot program that is written into the disklabel area of a
>      disk and a second-stage boot program that resides in a FFS file system on
>      the disk (named /boot).  Both parts of the boot are derived from a single
>      object file which is split by installboot during the installation pro-
>      cess.
>     bootfile       The name of the special object file (typically
>                     /usr/mdec/biosboot.sym) where the first and second stage
>                     boot programs to be installed reside.
> ------------------------------------------------------------------------------------
> Is that to say  mbr is contained in the biosboot.sym ?

No; "mbr" is a stanfart PC bootstrap program, localted in the first 512 bytes of
the disk (the first-stage boot program is written at the beggining of
a MBR partition, which never starts at the begginig of the disk). "mbr" will
look at the MBR partition table, locate the partition marked active and load
the small program located at the beggining of it. If it's a NetBSD partition,
this will be the first-stage boot program.

Manuel Bouyer <>