On Fri, Dec 01, 2006 at 11:21:15PM +0100, Segher Boessenkool wrote:
If not, what IS easily accessible besides the boot ROM?
In general? Nothing, not necessarily the boot ROM even!
I was trying to think outside the box. Is there any way to affect the system in a way that is easy to measure? Power? Voltage? Any bit that is easy to tap works. It must not be intended for communication, a side-effect is fine, as long as it is portable. (Ie. certain instructions executed in a certain order => CPU draws more power.) A bit wild, but simple to implement.
I think that we are going into a world where we have to figure out usb debug port.
It's certainly one good debugging option but maybe not the only good one.
And *all* these options require special (extra) debug hardware, no good for the end user.
We have to make sure the code never fails that early then. He-he.
I don't think that the PCI initial setup for USB debug is going to be impossible -- the vendors have to debug these boards too. All the boards I have used lately have a very straightforward path to USB, that could be set up in the ROMCC or CAR code.
I think it should be fairly simple on x86 too,
It can't be done in a generic way.
This is an interesting topic. See other thread about RAM.
//Peter