[LinuxBIOS] Support for recent chipset and powerful desktop CPU

[Peter Stuge]

On Wed, Nov 29, 2006 at 05:17:01PM -0700, ron minnich wrote:
> we are going to have to learn USB debug port. This problem is not
> going away.

Maybe we can find some other solution that is even easier to use.


On Thu, Nov 30, 2006 at 04:19:26AM +0100, Segher Boessenkool wrote:
> But yes, it's very unfortunate "modern" systems are
> so unfriendly to low-level bringup.  At the very least
> it makes it really really hard to have some uniform
> ("generic") working early setup code.

What other buses are usually available, that we could abuse to get
output with little hardware effort required?

While I would love to see an affordable PLCC thing that implements a
reads-make-a-write protocol it's not ready today nor tomorrow, while
the KN9 Ultra is getting older already.

What signals can be twiddled at, or soon after, power on?

Ideally we want a channel that is not required at all for bringup.

Ideally it would be able to run at both kHz and MHz to test/provoke
timing issues, but if single speed I guess kHz is easier to handle.


LPC
Pro: Available immediately after power on
Con: Logic needed to decode
Con: Mechanical issue, hard to hook up

DRAM
Pro: Easy to make/get/order PCBs that fit
Con: Not easily accessible without setting up DRAM controller
(Is this the case?)
Con: Need fast logic to decode.
(Is this the case? Can modern DRAM controllers be set to run slowly?)

IDE
Pro: Simple 8-bit PIO, easy to interface with
Con: Needs SuperIO running, at least a little, like the serial port.


What other candidates are there? What can code do that is easy to
measure? Power? Voltage? One bit is enough. Am I insane? :)


//Peter