[coreboot] patch: first steps to VSA support in v3

Marc Jones marc.jones at amd.com
Wed Jan 23 20:06:31 CET 2008



ron minnich wrote:
> These are incomplete and will continue to evolve, but I want to see if
> I can get it working at all.
> 
> attached.
> 
> ron

> vm86.c: make some assembly symbols .globl so that vmssetup.c can use them. 
> Add two ops to pci21 support that were define in vsmsetup.c in v2.
> I am pretty sure that the 66 is 66 Mhz, as in PCI bus clock; anyone know? 
> the second is probably 500, as in 500 Mhz, as in CPU clock. The values
> don't actually matter all that much, AFAIK. 
...
> + case 0xBEA7:
> + *eax = 66;
> + break;
> + case 0xBEA4:
> + *eax = 500;
> + break;
> }
> return res;
> } 

Ron,
Here is the documentation to go with the two int15 calls.

I15GetCpuSpeed
in:
AX = BEA4
BX = 4E53

out:
Retrieves CPU speed in AX

I15GetPCISpeed
in:
AX = BEA7
BX = 4E53

out:
Get PCI Bus Speed in AX


BUT, I don't think that you need them. VSA should default to reasonable 
settings without the in15 calls. I need to test it in v2 this afternoon. 
If VSA does require them I would rather change VSA. There is no reason 
it can't get the pci speed and cpu speed from the MSRs. Either way, i 
don't think you need to add it to v3.

Marc



-- 
Marc Jones
Senior Firmware Engineer
(970) 226-9684 Office
mailto:Marc.Jones at amd.com
http://www.amd.com/embeddedprocessors






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