coreboot-kgpe-d16/Documentation/releases/coreboot-4.22-relnotes.md

Upcoming release - coreboot 4.22

The 4.22 release is planned for mid-November, 2023

Update this document with changes that should be in the release notes.

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• See the past few release notes for the general format.
• The chip and board additions and removals will be updated right before the release, so those do not need to be added.
• Note that all changes before the release are done are marked upcoming. A final version of the notes are done after the release.

Significant or interesting changes

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x86: support .data section for pre-memory stages

x86 pre-memory stages did not support the .data section and as a result developers were required to include runtime initialization code instead of relying on C global variable definition.

Other platforms do not have that limitation. Hence, resolving it helps to align code and reduce compilation based restriction (cf. the use of ENV_HAS_DATA_SECTION compilation flag in various places of coreboot code).

There were three types of binary to consider:

1. eXecute-In-Place pre-memory stages
2. bootblock stage is a bit different as it uses Cache-As-Ram but the memory mapping and its entry code different
3. pre-memory stages loaded in and executed from Cache-As-RAM (cf. CONFIG_NO_XIP_EARLY_STAGES).

eXecute-In-Place pre-memory stages (#1) relies on a new ELF segment as the code segment Virtual Memory Address and Load Memory Address are identical but the data needs to be linked in cache-As-RAM (VMA) but to be stored right after the code (LMA).

bootblock (#2) also uses this new segment to store the data right after the code and it loads it to Cache-As-RAM at runtime. However, the code involved is different.

Not eXecute-In-Place pre-memory stages (#3) did not really need any special work other than enabling a .data section as the code and data VMA / LMA translation vector is the same.

Related important commits:

• c9cae530e5 ("cbfstool: Make add-stage support multiple ignore sections")
• 79f2e1fc8b ("cbfstool: Make add-stage support multiple loadable segments")
• b7832de026 ("x86: Add .data section support for pre-memory stages")

Toolchain updates

• Upgrade GMP from 6.2.1 to 6.3.0
• Upgrade binutils from 2.40 to 2.41
• Upgrade MPFR from 4.2.0 to 4.2.1

Additional coreboot changes

The following are changes across a number of patches, or changes worth noting, but not needing a full description.

• Changes that only need a line or two of description go here.

Platform Updates

• To be filled in immediately before the release by the release team

Plans to move platform support to a branch

• Section to be filled in or removed after discussion

Statistics from the 4.21 to the 4.22 release

• To be filled in immediately before the release by the release team

Significant Known and Open Issues

• To be filled in immediately before the release by the release team