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20231021 errata regarding fam15h rom file names 

Signed-off-by: Leah Rowe <leah@libreboot.org>
master
Leah Rowe 2023-10-28 21:35:45 +01:00
parent 24347a8362
commit ce6d9da778
2 changed files with 58 additions and 0 deletions
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5
site/freedom-status.md
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@ -276,6 +276,11 @@ technically required, but highly recommended. To remove, do:
cbfstool filename.rom remove -n cpu_microcode_blob.bin
On ASUS KFSN4-DRE, KCMA-D8 and KGPE-D16 boards, do this instead:
cbfstool filename.rom remove -n microcode_amd.bin
cbfstool filename.rom remove -n microcode_amd_fam15h.bin
[Releases after Libreboot 20230423 will provide separate ROMs with microcode
excluded, alongside default ones with microcode included.](news/microcode.md)

53
site/news/libreboot20231021.md
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@ -1136,6 +1136,9 @@ so the relevant acpica tarball was mirrored to Libreboot rsync at last minute.
Post-release errata
===================
Insertion of PIKE2008 ROMs, i945 bootblock copy
-----------------------------------------------
Empty PIKE2008 ROMs not inserted in KCMA-D8 and KGPE-D16 ROMs.
The 64KB bootblock isn't copied on ThinkPad X60 and T60 ROM images. This has
@ -1165,3 +1168,53 @@ Without the empty PIKE2008 ROM, SeaBIOS will hang on those AMD boards.
And without the bootblock copied on X60/T60 ROMs, flashing will result in a brick
under these conditions: bucts not reset and ROM flashed successfully, and/or
flashing the ROM from LenovoBIOS to Libreboot.
Fam15h microcode wrongly not detected as inserted
-------------------------------------------------
On those boards, `target.cfg` files specified `microcode_required="n"`, and
the logic in the release script renames ROM images according to this rule:
* If `cpu_microcode_blob.bin` exists in CBFS, copy the ROM to provide one
with this file removed.
* If the file doesn't exist in the first place, *move* (rename) the file
accordingly under the new name.
* In either of the above cases, `.rom` is replaced at the end
with `_nomicrocode.rom`, in any image that either has the microcode removed,
or if it wasn't there to begin with.
On these AMD boards (fam10 and fam15h), namely KCMA-D8, KFSN4-DRE and KGPE-D16,
the microcode is inserted into CBFS as two files,
namely `microcode_amd.bin` and `microcode_amd_fam15h.bin` - and the bug is
precisely that lbmk detected (based on only checking `cpu_microcode_blob.bin`)
no microcode, and thus *moved* (renamed) to names ending
in `_nomicrocode.rom`.
In other words, the Libreboot 20231021 ROM images for those boards *all*
contain microcode updates in them, but they all have `nomicrocode` in the ROM
file names. This was previously assumed to actually be the case, until an audit
revealed otherwise (as of 28 October 2023).
This isn't really a problem, it's not a "bug" per se, just a naming error.
The fix has been implemented with *this* patch:
<https://browse.libreboot.org/lbmk.git/commit/?id=83bf23766040d5e1642b8c80d975953c1c34f876>
To put it simply: this will not be fixed. Instead, the above patch
unsets `microcode_required`, so it defaults to `y`. Therefore, the ROM images
in next release will contain microcode (as they all do, now) and they will
not contain `nomicrocode` in the ROM image file names.
On ASUS KFSN4-DRE, KCMA-D8 and KGPE-D16 boards, do this to remove microcode:
cbfstool filename.rom remove -n microcode_amd.bin
cbfstool filename.rom remove -n microcode_amd_fam15h.bin
We recommend *keeping* microcode updates, for reasons written in the [Binary
Blob Reduction Policy](policy.md).
There is also the recent launch of the [Canoeboot project](https://canoeboot.org/),
an official sister project of Libreboot, maintained by Leah Rowe who also leads
the Libreboot project; Canoeboot release images do not ever contain microcode
updates in them. This is precisely why it will not be fixed in lbmk to fix
the naming issue. The behaviour is simply disabled instead, becasue there's no
point adding further complexity to the build system.