[LinuxBIOS] Read / Write to CMOS

[mack stout]

Hello list,

I'm somewhat new to bios programming... but i have a handful of boxes (with
Award Bios) that I need to set to pxeboot remotely. I was thinking that I
might achieve this by dumping the CMOS (cat /dev/nvram > file) of a box with
pxeboot on, and then writing it to a box that has pxeboot turned off.

I will actually be surprised if a quick hack like this would actually work,
as I imagine its not that simple. But I was hoping that I might get some
information about what settings are actually stored in CMOS, if they're
changeable, if there's a GPL'd utility to facilitate this process.

Does linuxbios support altering bios settings from userspace?

Ben

[ron minnich]

On 1/22/07, mack stout <[e-mail]> wrote:
> Does linuxbios support altering bios settings from userspace?

it's easy to do this.

You need the simple tools that read and write cmos.

Attached.

ron

[Ben Racher]

ron minnich wrote:
> On 1/22/07, mack stout <[e-mail]> wrote:
> > Does linuxbios support altering bios settings from userspace?
>
> it's easy to do this.
>
> You need the simple tools that read and write cmos.
>
> Attached.
>
> ron
> perfect! just what I had been looking for, and it even works fine with 
> phoenix award bios! I just set the settings that I want to change, dump 
> it, and then write it to clients (with exact same hardware) and the 
> settings are applied. amazing!

now i just need to learn what actually happens in these 35 lines of code 
:-) what library does
outb(regno, 0x70); come from? and 0x70 represents the memory where cmos 
starts at?

ben

[David Hendricks]

The functions come from asm/io.h, 0x70 is the CMOS memory address I/O port,
and 0x71 is the CMOS memory data I/O port. It looks like
http://www.faqs.org/docs/Linux-mini/IO-Port-Programming.html has some good
information on this topic. I know "The Undocumented PC" by Van Gilluwe has a
pretty thorough discussion of the CMOS ports as well.

On 1/23/07, Ben Racher <[e-mail]> wrote:
> ron minnich wrote:
> > On 1/22/07, mack stout <[e-mail]> wrote:
> > > Does linuxbios support altering bios settings from userspace?
> >
> > it's easy to do this.
> >
> > You need the simple tools that read and write cmos.
> >
> > Attached.
> >
> > ron
> > perfect! just what I had been looking for, and it even works fine with
> > phoenix award bios! I just set the settings that I want to change, dump
> > it, and then write it to clients (with exact same hardware) and the
> > settings are applied. amazing!
>
> now i just need to learn what actually happens in these 35 lines of code
> :-) what library does
> outb(regno, 0x70); come from? and 0x70 represents the memory where cmos
> starts at?
>
> ben