[LinuxBIOS] Overview

Dear All,

I'm completely new to LinuxBios, and I'm trying to understand exactly what 
it does, and what it offers.  Trying to decide exactly how interested I 
am.  Could you please forgive my ignorance and clarify the following for 
me please:

Does LinuxBios run on the main processor or on some auxiliary processor?

What is the typical power consumption of a LinuxBios moboard running the 
minimum number of devices to do basic communication over ethernet - 
hopefully only the moboard and the network card if it isn't already on the 
moboard will require power, then I need to know processor consumption - 
here the earlier question about what does the processing becomes relevant.

Can LinuxBios be used to do complicated wake-on lan?  Here minimal power 
consumption in the idle state becomes important to me.  (question of 
fairly high interest to me)

Does LinuxBios help with running multiple operating systems 
simultaneously? (high interest)

Does it accelerate booting, because where previously first the bios 
loaded, then grub, then the OS proper, now perhaps booting can go straight 
from LinuxBios to OS?

How often can one typically write to the bios before it won't take any 
more changes?  I understand it's flash, so I expect few thousand times, 
more if one rotates which memory blocks one uses, but on the other hand 
this isn't exactly flash that is designed to be rewritten very often, as 
far as I understand anyway!  Can one fairly easily and at a competitive 
price buy replacement chips?

I very much appreciate any help you can give, because you've already done 
this kind of stuff.

A short introduction is probably in order:  I'm a mathematician, so a bit 
of an amateur where computer science is concerned.  I'm getting into 
writing linux device drivers at the moment.

Best Wishes, Max

[Richard Smith]

On 4/25/06, [e-mail]  wrote:
> I'm completely new to LinuxBios, and I'm trying to understand exactly what
> it does, and what it offers.  Trying to decide exactly how interested I
> am.  Could you please forgive my ignorance and clarify the following for
> me please:

Have you read all the info at linuxbios.org?  That should help.
> Does LinuxBios run on the main processor or on some auxiliary processor?

LinuxBIOS replaces the system BIOS so it rus on the "main" processor.
> What is the typical power consumption of a LinuxBios moboard running the
> minimum number of devices to do basic communication over ethernet -
> hopefully only the moboard and the network card if it isn't already on the
> moboard will require power, then I need to know processor consumption -
> here the earlier question about what does the processing becomes relevant.

The power consumption of most onboard devices will be swamped by the
power consumption of the CPU.  Next in line (or even greater) would be
a high powerd graphics card.  Since the power consumption of a
mainboard depneds on the type of the mainboard, the design of the
mainboard, and load of the CPU there is no easy answer to your
question.  Some one would actually have to measure it for a specific
mainboard setup.

For example a Dual opteron setup is going to pull way more juice than a Geode.
> Can LinuxBios be used to do complicated wake-on lan?

LinuxBIOS is GPL so it can do _whatever_ you code it to do. *grin*
Currently I don't know of any wake-on-lan implementations for the
supported mainboards.  But perhapas someone else does.
> Does LinuxBios help with running multiple operating systems
> simultaneously? (high interest)

No.
> Does it accelerate booting,

Yes.
> because where previously first the bios
> loaded, then grub, then the OS proper, now perhaps booting can go straight
> from LinuxBios to OS?

Even better than that.  LinuxBIOS can be customized to take out most
of the fat in a normal bios.  A linux prompt in 3 seconds is not
unheard of.  A lot depends on the type of media you boot from.
> How often can one typically write to the bios before it won't take any
> more changes?

I do embedded systems where we use flash parts a lot and I've never
run into a case where I've reached the write limit of a flash during
developement.  Its largely a non-issue.
> I understand it's flash, so I expect few thousand times,

The minimum I've ever seen was 10,000 cycles.  Most are 100,000
cycles. Some nowdays are 1M cycles.  This is also a worst case rating.
 ie running at the temp extreme and the lowest supply voltage.
> more if one rotates which memory blocks one uses, but on the other hand
> this isn't exactly flash that is designed to be rewritten very often, as
> far as I understand anyway!  Can one fairly easily and at a competitive
> price buy replacement chips?

Yes.  Digikey and Mouser have most of the popular parts.  And you
don't need the exact same part just one that is the same size and the
same speed and same package/pinout.

[Peter Stuge]

On Tue, Apr 25, 2006 at 01:11:55PM +0100, [e-mail] wrote:
> Dear All,
>
> I'm completely new to LinuxBios, and I'm trying to understand
> exactly what it does, and what it offers.  Trying to decide exactly
> how interested I am.  Could you please forgive my ignorance and
> clarify the following for me please:

Perhaps you've already checked out the wiki on
http://wiki.linuxbios.org/ ? It has useful information both on macro
and micro levels.
> Does LinuxBios run on the main processor or on some auxiliary processor?

On the main processor.
> What is the typical power consumption of a LinuxBios moboard
> running the minimum number of devices to do basic communication
> over ethernet - hopefully only the moboard and the network card if
> it isn't already on the moboard will require power, then I need to
> know processor consumption - here the earlier question about what
> does the processing becomes relevant.

This depends completely on the hardware. LinuxBIOS can be configured
to disable or just disregard any hardware in the system that can be
disabled (usually this means leaving PCI devices untouched) but
whether the hardware does powersaving or not is outside LinuxBIOS'
control.
> Can LinuxBios be used to do complicated wake-on lan?  Here minimal
> power consumption in the idle state becomes important to me. 
> (question of fairly high interest to me)

LinuxBIOS doesn't generally stay resident in any way after starting
the OS either, the exception may be the recent VSA support that is
specific to the Geode family of System-on-Chip products from AMD.

Since LinuxBIOS is no longer running, this depends on the OS.
> Does LinuxBios help with running multiple operating systems
> simultaneously? (high interest)

No.
> Does it accelerate booting, because where previously first the bios
> loaded, then grub, then the OS proper, now perhaps booting can go
> straight from LinuxBios to OS?

Yes. I believe the boot time record is around three (3) seconds
although this will require ideal circumstances. Expect LinuxBIOS to
always be faster than a factory-supplied closed-source BIOS though.
Boot time varies heavily with specific mainboards and their quirks,
which affect LinuxBIOS as well as the OS. Solid-state storage (flash)
is a must for the optimal times.
> How often can one typically write to the bios before it won't take
> any more changes?  I understand it's flash, so I expect few
> thousand times, more if one rotates which memory blocks one uses,
> but on the other hand this isn't exactly flash that is designed to
> be rewritten very often, as far as I understand anyway!

I'd expect at the very least tens of thousands write cycles, but more
commonly hundreds of thousands. Anyway it's more than enough for
development, but probably not something you would want to depend on
in the field. (self-flashing systems etc.)
> Can one fairly easily and at a competitive price buy replacement
> chips?

Lots of flash parts are interchangeable. Check the specs for the
factory-installed part and find a replacement from your favorite
flash manufacturer. Add support to the LinuxBIOS auxiliary utility
flashrom if the particular chip isn't supported yet.

Most if not all flash manufacturers have distributors that will
gladly sell large quantities (1k+) of chips. Those willing to deal in
smaller quantities are fewer, but still exist. You'll usually have to
buy at least one full package. (typically PLCC or DIP plastic tubes
with 20-40 chips) Prices depend on flash size, but stay around a few
dollars per part.
> A short introduction is probably in order:  I'm a mathematician, so
> a bit of an amateur where computer science is concerned.  I'm
> getting into writing linux device drivers at the moment.

Cool. Out of curiosity, what is your interest in LinuxBIOS?

//Peter

Thanks, Richard and Peter, that helped a lot.

I'd read the intro and the FAQ but not the wiki.  I shall probe the last 
but not until (apply industrial strength matchsticks) the morning in the 
old fashioned and comfortably un-pedantic sense of the sun coming up.

My primary interest just at the moment is having a low power device server 
that I can program to take various USB devices and also do provide some 
very basic network services that need to be on all the time if they're 
going to be any use at all.  However naturally if the technology has wider 
implications I'd be interested to know where it's going, just out of 
curiosity.  The fast booting sounds attractive.

The use of the main processor kills the thought of motherboards gaining a 
second, low power purpose in their powered down mode.  I suppose one could 
use wake on lan, use the processor for a short time and then shut down 
again however that isn't ideal.  I've looked at some purpose built 
embedded devices that run on linux and I'll probably use one of those. 
There are quite a lot to choose from!

Once again, thanks for your help.

Best Wishes, Max