"Thomas J. Merritt" <[EMAIL PROTECTED]> writes:
> |<><><><><> Original message from Eric W. Biederman <><><><><>
> |Ronald G Minnich <[EMAIL PROTECTED]> writes:
> |
> |> On 28 Aug 2001, Eric W. Biederman wrote:
> |> > I'd be suprised if they don't get it. At least the basics. For
> |> > things like the AMD760 the documentation spells out fairly clearly
> |> > where everything should be coming from. And the SPD isn't magic just
> |> > a label in silcon form that the manufacturers add to their DIMMS.
> |> >
> |>
> |> What we did see on one bios is that they didn't do as good a job with SPD
> |> as Ollie. I have also been told that BIOS programmers do a suboptimal job
> |> since there are so many SDRAMs out there with SPD data that is wrong.
> |
> |Using SDRAMS with incorrect serial EEPROMS is a lame excuse, for not
> |using the SPD data.
>
> Ok, so what do you recommend the BIOS do in the case that the SPD data
> is wrong for the SDRAM chips and configuration of the DIMM?
First that DIMM is a manufacturing error so supporting it is being nice.
For supporting having a seperate mode that reads hard coded parameters
someone set would be fine. Even detecting such a bad dimm is a challenge.
> |I think what happens is that board manufactures license a BIOS kit
> |from award, or ali. Customize it for their board. And then ship the
> |board. But I don't think this gets much code reuse, between different
> |board manufacturers. And because you have so many people doing it you
> |have serious variations in quality.
>
> I haven't looked at any of the x86 chipsets very carefully, but to
> properly use SPD data on other boards I'm familiar with, requires knowing
> information about board layout and signal propogation. How are your
> factoring these parameters in to your x86 chipset support?
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.
>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.
Eric
