Using int 13 while BSD is running
Erik Trulsson
ertr1013 at student.uu.se
Wed Mar 10 09:24:04 PST 2004
On Wed, Mar 10, 2004 at 08:49:17AM -0800, Jason Dictos wrote:
>
>
> > To Jason: take care not to *write* anything to the disk via int 13h.
> > I still don't think I understand why you are using FreeBSD for this
> specific purpose. Why if you just >spend time escaping from the OS?
>
> We actually _like_ protected mode, it allows us to be more flexible and our
> code doesn't have to be bastardized with 16 dos compilers ;). However in dos
> we have garanteed hard drive support via int13 (Well almost garanteed, but
> if an os can boot of the computer, we can access the disk), and I'm looking
> for the same sorta garantee in BSD. People will be using this with raid
> controllers, scsi hard disks, and ide drives (Server recovery), so there
> will be many times when the hardware running the hd requires specific
> support, which BSD may or may not have, point is we dont' want to manage
> that.
>
> Make sense?
Just because you can boot from the disk does not mean that the BIOS can
read the whole disk.
As an example I have an old computer running FreeBSD with a 1GB disk.
The BIOS in this computer cannot handle disks larger than 512MB (which
was a quite common limitation in older BIOSs). I can however boot from
this disk since all the files needed for booting reside below the 512MB
mark. Once I have booted FreeBSD I can access the whole disk precisely
because FreeBSD does *not* use the BIOS, but use its own routines.
--
<Insert your favourite quote here.>
Erik Trulsson
ertr1013 at student.uu.se
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