[coreboot] AMD CAR questions

[Rudolf Marek]

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> Thanks for the analysis.  I can see it being useful for other things too.

Ok.

> My understanding was that CAR refers to L2.  As long as nothing gets
> replaced from the L2, everything is as it should be.  ROM contents can
> always be fetched again, so that's not critical for correctness.

This is OK, but L2 CAR is in more detail described in fam11h otherwise AMD
always just speaks about L1 CAR. the fam11h needs some extra tweaks to various
MSR to disables speculative fills if I remember correctly. This is the reason
why I see this a bit dangerous, perhaps older CPUs needs this too.

I think we should mark the XIP region as WP instead of WB (check  the fam11h BKDG).

Anyway - I tried with UC copy looks like it is not so slow...

I have in works the patch for the register clobber cleanup plus I will do some
patch for saving the coreboot mem to resume area... but perhaps on Sunday.
Tomorrow bit of skiing, but if you are curious, here is the patch. It just fixes
the clobber stuff for the assembly routines, it has bitten me already while
dumping the MSRs... the ECX value contained some garbage, and rdmsr did some
exception.

The memcpy code is from Linux kernel.

Rudolf
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