On Tue, Oct 27, 2009 at 6:06 AM, Darmawan Salihun <darmawan.salihun@gmail.com> wrote:

What is the BIOS RAM in AMD SB7XX used for?

Looks like scratchpad memory to me. From the public doc:

3.3 BIOS RAM
The SB700 has 256 bytes of BIOS RAM. Data in this RAM is preserved until RSMRST# or S5 is
asserted, or until power is lost.
This RAM is accessed using index and data registers at CD4h/CD5h.

Might it be enough to act as a very, very small cache-as-RAM substitute until CAR can be set up?

On Tue, Oct 27, 2009 at 6:06 AM, Darmawan Salihun <darmawan.salihun@gmail.com> wrote:

Is it to buffer the BIOS contents from SPI flash chip prior to
execution of the very first instruction?
I recall that it's impossible to execute code directly in an SPI chip.

That's correct, afaik.