the following patch was just integrated into master: commit a01695bf9ac5ad401950af96682b494127ad8a8d Author: Nico Huber nico.h@gmx.de Date: Wed Dec 14 23:48:09 2016 +0100
Revert "arch/x86/smbios: Correct manufacturer ID"
This reverts commit c86da67436827c25919a2f5966049485a58fc984.
Alas, I have to disagree with this in every single line. The comment added to the top of the file only applies to a single function therein which sits over a hundred lines below. That's not much helpful. More- over, the link in the comment is already down ofc.
The comment is also irritating as it doesn't state in which way (enco- ding!) it applies to the code, which presumably led to the wrong in- terpretation of the IDs.
At last, if anything should have changed it is the strings, the IDs are resolved to. `smbios_fill_dimm_manufacturer_from_id()` has to resolve the IDs it gets actually fed and not a random selection from any spec.
Since I digged into it, here's why the numbers are correct: The func- tion started with the SPD encoding of DDR3 in mind. There, the lower byte is the number of a "bank" of IDs with an odd-parity in the upper most bit. The upper byte is the ID within the bank. The "correction" was to clear the parity bit for naught. The function was later exten- ded with IDs in the DDR2-SPD encoding (which is actually 64-bit not 16). There, a byte, starting from the lowest, is either an ID below 127 plus odd-parity, or 127 which means look in the next byte/bank. Unused bytes seem to be filled with 0xff, I guess from the 0xff2c.
Change-Id: Icdb48e4f2c102f619fbdca856e938e85135cfb18 Reviewed-on: https://review.coreboot.org/17873 Tested-by: build bot (Jenkins) Reviewed-by: Matt DeVillier matt.devillier@gmail.com Reviewed-by: HAOUAS Elyes ehaouas@noos.fr Reviewed-by: Paul Menzel paulepanter@users.sourceforge.net Reviewed-by: Martin Roth martinroth@google.com
See https://review.coreboot.org/17873 for details.
-gerrit