"Thomas J. Merritt" <[EMAIL PROTECTED]> writes:
> I agree that a DIMM with bad SPD data is busted hardware and supporting it
> is being nice. But early on when SPD's were added to DIMMS most of the
> DIMMS that came through had the SPD programmed with all FF's. Recent
> DIMMS seems better, but I have seen differences in interpretations of the
> definitions. Given that SPD data could not be relied upon early on, I think
> it is understandable that BIOS vendors would not overly rely upon
> it.
At first yes.
> Given that some DIMM vendors are consistiently getting get the SPD data
> right, I would recommend pushing the memory controller to the limits
> and let the ones with bad SPD data just fail.
Definentily. The context this was comming from was for DDR DIMMS and
at least for the AMD760 you don't really have a choice but to use the
SPD data.
> |For all of the parameters I am aware of that are board specific I have
> |a lookup table that you can define per motherboard. And if you have a
> |really nasty requirement you can even have a subroutinte that you can
> |have per motherboard, but I haven't seen anything that would require
> |that yet.
>
> This seems pretty reasonable, are you able to ID boards reliably?
Mostly it is a compile option... I guess there are some boards
where you can even ask it for a hardware revision. But for now we just
compile the code appropriately. The linuxBIOS tree breaks up nicely
by motherboard.
The large scale production issues leave a little to be desired as we
are just now getting to a point where we can go into large scale
production...
> |From what I have seen x86 chipsets haven't required a lot of knowledge
> |about board layout and signal propogation for setting up SDRAM. You
> |can suprise me. I'm not a god in this area just comptetent which was
> |my point early. In truth I have seen more problems with registers
> |left unitialized that take on random values then I have with timing
> |information per motherboard.
>
> Uninitialized registers are definitely a problem. Particularly the
> undocumented ones, hopefully x86 vendors are better about this.
Some are better then others.
It looks like codegen has been down the cross platfrom BIOS route
before. Are you looking at working with the linuxBIOS?
Eric
