Hi,
On 02/13/2017 10:22 AM, Timothy Pearson wrote:
<snip>
For [2] we have been working on prototype for Apollolake that does
pre-memory MPinit. We've got to a stage where we can run C code on
another core before DRAM is up (please do not try that at home, because
you'd need custom experimental ucode).
In addition to the very valid points raised by others on this list, this
note in particular is concerning. Whenever we start talking about
microcode, we're talking about yet another magic black box that coreboot
has no control over and cannot maintain. Adding global functionality
that is so system specific in practice as to rely on microcode feature
support is not something I ever want to see, unless perhaps the relevant
portions of the microcode are open and maintainable by the coreboot project.
I am just talking about BIOS shadowing. This is a pretty standard
feature, just that not every SoC implement it by default. Naturally, we
would be only adding new code if it became publicly available. I believe
shadowing works on many existing CPUs, so no, it is not "use this custom
NDA-only ucode" to get the stuff working.
Andrey
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