[OpenBIOS] OpenBIOS: reality check

Aaron M. Gowatch aarong at wired.com
Sun Mar 1 11:36:48 CET 1998

On Sun, 1 Mar 1998, David Woodhouse wrote:

> Not so. At least on the SX164 we have, it knows about the filesystem. Anyway,
> the phrase "the location of which is described by values stored on the first
> 512 byte sector" sounds suspiciously like understanding disk partitions to me.

Ahh... the Windows NT AlphaBIOS that runs on the PC164.  Its a lot like
the Windows NT ARC firmware, but it is not SRM.

What does reading raw sectors off of a disk have to do with partitions? 
Before any disk has partitions or even filesystems on it, it has sectors. 
Do you think the MBR is a partition?  You store these values in the first
512 byte sector of raw disk and you read them.

> The SRM firmware understands at least FAT, and possibly also NTFS partitions.
> Certainly it's capable of loading second-stage bootloaders like "LINLOAD.EXE"
> from a FAT floppy disk. I believe that even the emergency firmware update is
> managed from a FAT floppy.

Again, the Windows NT AlphaBIOS, tailored specifically for running Windows
NT, has support for these filesystems.  It is not SRM.  I dont see the
point in developing such OS specific BIOS extensions.

> Making new filesystems just so that the BIOS can access them easily is not 
> practicable. Neither is the idea of dedicating a partition to BIOS extensions.
> Simple read-only filesystem support can be kept fairly small, and is going to 
> be required by UNIX people to load either the second-stage bootloader or the 
> kernel itself.

Agreed, creating new filesystems is probably not practical.  But saying
that a filesystem is required in order to boot UNIX is entirely false. 
The concept of reading sectors directly from disk independent of
partitions or filesystem is not a new one.  I'd suggest that you read the
SRM Firmware HOWTO: 



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