march 2023 libreboot release coming soon
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libreboot202303xx.md
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usa-libre-part3.md
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usa-libre-part2.md
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fedfree.md
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% March 2023 Libreboot release expected soon
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% Leah Rowe
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% 16 March 2023
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Introduction
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============
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iDevelopment on Libreboot has largely focused on fixing issues since the
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December 2022 release, and I very recently updated coreboot revisions (for
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x86 boards) to a newer February 2023 revision. The GRUB and SeaBIOS payloads
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have also been updated to newer revisions from upstream. A few minor fixes
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here and there (e.g. VRAM size on GM45 machines causing instability, heavy
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code re-factoring of nvmutil, minor build system tweaks).
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The build system in Libreboot has matured quite a bit since the reboot of the
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project back in 2021, to the point where much less work on the build system is
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needed these days. The focus from now on is going to be on new hardware support
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and hardware testing (an ambitious agenda, for which board maintainers will be
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needed).
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Saturday, 18 March 2023
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-----------------------
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I'll have more to say on the day of release, via Change Log, but
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I'm basically confident that I'll have a new Libreboot release out
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the door on ~Saturday, 18 March 2023. This release will be marked *testing*,
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because there are still many blockers preventing the declaration of a stable
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release, but in practise all of the boards that have pre-built ROMs will
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at least boot and be usable.
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The current state of Libreboot is that it's ready for a new testing
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release, without many major issues, but for one major problem:
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Haswell S3 issue (and fix)
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==========================
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The problem
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-----------
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The S3 suspend/resume feature on Haswell (ThinkPad T440p/W541) is still
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broken. Resuming from suspend results in a cold boot. This is due quirks in
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how Intel's MRC blob works (for raminit), coupled with how Libreboot configures
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both the IFD and CBFS size in coreboot.
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I now know of two possible ways to fix it, and I'm confident that one or both
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will be effective:
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Fix
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---
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The Heads project, which is another coreboot distro similar to Libreboot,
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recently added T440p support, but they fixed the S3 bug. The relevant
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differences in their firmware, compared to Libreboot, is as follows:
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* IFD changes, related to read/write bits. Most likely irrelevant for the
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purpose of this
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* CBFS size on theirs is set to 8MB, and the reasoning is explained here:
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<https://github.com/osresearch/heads/pull/1282#issuecomment-1400634600>
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Basically, the `mrc.bin` blob provided for raminit on Haswell (T440p/W541 etc)
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caches the coreboot code in ways that Libreboot currently screws up. At the
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time of this post, I'm currently adapting the changes from Heads and conducting
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tests. I believe their changes will fix it.
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However, 8MB CBFS is far from ideal, as Libreboot currently provides much
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larger size of ~11.7MB CBFS size (same size as that of the BIOS region, per
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rules set in the intel flash descriptor).
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Libre MRC replacement
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---------------------
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Angel Pons (`hell` on coreboot IRC) has been reverse engineering `mrc.bin` on
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Haswell platforms. I've learned that they have in fact released a WIP of their
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work, and it apparently works well. You can find the patch set here:
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<https://review.coreboot.org/c/coreboot/+/64176/5/>
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When you follow up on the chain of commits, it ends here:
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<https://review.coreboot.org/c/coreboot/+/64198/5>
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The MRC blob provides initialisation of the memory controller. Hell's work
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implements a libre replacement of it, with source code.
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Plan
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----
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Unrelated to the S3 issue, I'm testing the differing IFD setup from Heads,
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but inserted into Libreboot.
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Then I'm going to *ignore* the 8MB CBFS config option in Heads, and retain
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the current larger CBFS size set in Libreboot. I shall do this, while
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merging Angel's patches into Libreboot (coreboot has not yet merged them,
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so the patches are under review, but Libreboot has integrated unmerged patches
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before, from coreboot).
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If the libre raminit works, then I'll re-test the S3 suspend/resume function.
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Whether or not that fixes it, I will start building the Libreboot release.
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(my first priority, per Libreboot's binary blob reduction policy, is to provide
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libre code wherever possible - broken S3 suspend/resume would not be enough to
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make me retain the `mrc.bin` blob).
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I was hoping to have the release out *today*, but instead I've decided to
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announce that today that I'm working on it.
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This business with Haswell is the only major issue I've yet to fix in
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Libreboot, at least for x86.
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*ETA Saturday, 18 March 2023 for release. Libreboot 20230318.*
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