Re: [FreeBSD 5.1] Large hard disks vs old BIOS

From: Steven Maesslein (nobody_at_nowhere.invalid)
Date: 10/29/04 

Date: Fri, 29 Oct 2004 13:39:19 +0200

On 28 Oct 2004 21:08:04 GMT, Jehannes coughed into
comp.unix.bsd.freebsd.misc and left this in
<Xns9590EB5CA3B9Fjohnbeevernl@194.109.133.133>:

> Is there a way to make FreeBSD 5.1 recognize hard disks larger than the
> BIOS supports?
> I read somewhere that Linux could do it through direct access to the
> hardware.

Both Linux and FreeBSD throw the BIOS out the window when it comes to
disk access so that they have something that'll work in protected mode.
One of the (fortunate) side effects of this is no longer being bound by
the 1024 cylinder limit. The only time the BIOS (which only works in
real mode) intervenes is in order to boot the machine, so this means
that your kernel has to reside in an area which is accessible to the
BIOS so that it can be loaded. However, once it is loaded and it has
replaced the disk I/O routines in the BIOS, there are no practical
restrictions. My previous machine's BIOS only handled 8GB disks, like
yours, but it worked with an 80GB disk no problems. 

-- 
Steve
If you have watched a TV series only once, and you watch
it again, it will be a rerun of the same episode.

Relevant Pages

  • Re: Support HDIO_GETGEO on device-mapper volumes
    ... grub used HDIO_GETGEO when running under Linux. ... There's the translation that the BIOS (and thus DOS, PartitionMagic, ... disk in a compatible way. ... the MBR values are not guaranteed to be correct if you want ...
    (Linux-Kernel)
  • [ANNOUNCE] ACPI BIOS Guideline for Linux
    ... Linux is urgently missing and should get published. ... I mainly try to get feedback from OEMs and BIOS developers, ... ACPI BIOS checks whether Linux is running...). ...
    (Linux-Kernel)
  • Reporting ThinkPad BIOS bugs
    ... on a T60p/T61p and test it on a Linux box that isn't one of those types ... Ask the BIOS authors. ... Even if the person reading the report doesn't know Linux well, ... "One disk to rule them all, ...
    (Linux-Kernel)
  • Re: 48-bit LBA enhancement to the ATA interface - Hard disk drive (HDD) interface questio
    ... ' =JeffH ' wrote: ... I've been told that the limit on this machine is nominally a 120GB disk (on ... Some modest research indicates that this system (e.g. the BIOS) _might_ be ... This applies to Linux, but to Microsoft, just as well. ...
    (Ubuntu)
  • Re: Linux, BSD, and Unix are fundamentally insecure.
    ... Shutdown, insert disk, reboot, and log in. ... Should work on a large majority of boxes if their BIOS isn't set right. ... > machine and passed a command to GRUB that booted linux into the BASH ... > Windows doesn't have this flaw. ...
    (comp.unix.bsd.freebsd.misc)