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authorLeah Rowe <leah@libreboot.org>2023-03-18 22:44:34 +0000
committerLeah Rowe <leah@libreboot.org>2023-03-18 23:21:15 +0000
commitcffa5679295bffaeec76c7f72cbd7756495b3865 (patch)
tree4a015d65b6cc24633d67081ecfec2a6d65b3fd8e /resources/grub/background
parentbe3d7b7e69189055fbf8b7904336593a03a17ecd (diff)
haswell (lenovo t440p/w541): fix S3 suspend/resume
MRC caches in a certain way, that Heads was able to work around in their build system, for this board. I've adapted the relevant config differences, from their project as of heads revision 96440b928acb06de5b925ea12014c9c280b23165 The downside is that CBFS now has to be 8MB in size. The upside is that the machine also boots much faster See: https://github.com/osresearch/heads/pull/1282/commits/f0792117efa177ded19878f652c5a28e8cc62a71 https://github.com/osresearch/heads/pull/1282#issuecomment-1400634600 I have not adapted their IFD changes, versus Libreboot, because theirs simply has a different version string, and uses different read/write permission bits for regions as defined in the IFD. This affects: t440p_12mb_mrc w541_12mb_mrc S3 suspend/resume still broken on these targets which use the libre MRC init (replacement code by Angel Pons, recently merged in lbmk): t440p_12mb w541_12mb With clever use of FMAP, the rest of the BIOS region might still be used. However, for our purposes, 8MB CBFS will do just fine. Heads's changes configure MRC so that caching is handled properly, for when the machine returns from sleep. Setting CBFS to be any higher will result in slower boot times, and broken S3 resume, due to MRC cache misalignment (this is based on my understanding, reading through the Heads project looking at their research on this). At some point in the future, Angel's libre MRC code will probably be finished, and merged, with more fine tuning possible to allow bigger CBFS sizes.
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