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 dochttp://developer.amd.com/assets/43366_sb7xx_bdg_pub_1.00.pdf :
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.