cbc561f64a
At the moment, this just gives some details on the MRC. Change-Id: I84e8ca2543b2e19b84a24f7d7032a4aedb6e9272 Signed-off-by: Tristan Corrick <tristan@corrick.kiwi> Reviewed-on: https://review.coreboot.org/c/30356 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Nico Huber <nico.h@gmx.de>
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mrc.bin
All Haswell boards supported by coreboot currently require a proprietary
blob in order to initialise the DRAM and a few other components. The
blob, named mrc.bin, largely consists of Intel's memory reference code
(MRC), but it has been tailored specifically for Chrome OS. It is just
under 200 KiB in size. Another name for mrc.bin is the system agent
binary.
Having a replacement for mrc.bin using native coreboot code is very
much desired, but it is not an easy task.
Obtaining mrc.bin
Unfortunately, it is not currently possible to distribute mrc.bin as
part of coreboot. Though, it can be obtained from a Haswell Chromebook
or Chromebox firmware image, and you might find one online. mrc.bin
can be extracted with the following command. If extracting from a
"standard" coreboot image, omit -r RO_SECTION.
cbfstool coreboot.rom extract -f mrc.bin -n mrc.bin -r RO_SECTION
Now, place mrc.bin in the root of the coreboot directory.
Alternatively, place mrc.bin anywhere you want, and set MRC_FILE to
its location when building coreboot.
ECC DRAM
When mrc.bin has finished executing, ECC is active on the channels
populated with ECC DIMMs. However, mrc.bin was tailored specifically
for Haswell Chromebooks and Chomeboxes, none of which support ECC DRAM.
While ECC likely functions correctly, it is advised to further validate
the correct operation of ECC if data integrity is absolutely critical.