[coreboot] Saving truncated preram CBMEM messages

[Paul Menzel]

Dear coreboot folks,


looking at the coreboot CBMEM console messages board status repository,
you’ll find a lot of truncated preram CBMEM console messages.

Currently the buffer size is 0xc00 – 3 kB, right –, which is too small
for quite some boards. The mainboard *Kabylake LPDDR3 RVP3* overrides
it to 0xd00.

So I am thinking about increasing it [1], but it’s of course not that
simple, especially as I don’t understand all the implications.

  Increasing this buffer reduces amount of available CAR
stack, and
 apparently DDR3 raminit already struggles with the amount of
 cachelines available on fam10/15
My first question is, what other downsides are there of increasing the
buffer size? I assume it’s unrelated to resulting usable RAM size, as
RAM sizes nowadays are much, much bigger? So would one megabyte be
reasonable/possible as a goal on boards supporting that?

So if their is consensus that it should be increased, what would a way
be forward? I assume, overriding it per mainboard is not so useful, as
these messages are mostly from the chipset, so it should be chipset
dependent?

Should that option be moved there?


Thanks,

Paul


[1] https://review.coreboot.org/18049/
   "arch/x86: Increase preram CBMEM console buffer size"