cbfs: Increase mcache size defaults

The CBFS mcache size default was eyeballed to what should be "hopefully
enough" for most users, but some recent Chrome OS devices have already
hit the limit. Since most current (and probably all future) x86 chipsets
likely have the CAR space to spare, let's just double the size default
for all supporting chipsets right now so that we hopefully won't run
into these issues again any time soon.

The CBFS_MCACHE_RW_PERCENTAGE default for CHROMEOS was set to 25 under
the assumption that Chrome OS images have historically always had a lot
more files in their RO CBFS than the RW (because l10n assets were only
in RO). Unfortunately, this has recently changed with the introduction
of updateable assets. While hopefully not that many boards will need
these, the whole idea is that you won't know whether you need them yet
at the time the RO image is frozen, and mcache layout parameters cannot
be changed in an RW update. So better to use the normal 50/50 split on
Chrome OS devices going forward so we are prepared for the eventuality
of needing RW assets again.

The RW percentage should really also be menuconfig-controllable, because
this is something the user may want to change on the fly depending on
their payload requirements. Move the option to the vboot Kconfigs
because it also kinda belongs there anyway and this makes it fit in
better in menuconfig. (I haven't made the mcache size
menuconfig-controllable because if anyone needs to increase this, they
can just override the default in the chipset Kconfig for everyone using
that chipset, under the assumption that all boards of that chipset have
the same amount of available CAR space and there's no reason not to use
up the available space. This seems more in line with how this would work
on non-x86 platforms that define this directly in their memlayout.ld.)

Also add explicit warnings to both options that they mustn't be changed
in an RW update to an older RO image.

BUG=b:187561710

Signed-off-by: Julius Werner <jwerner@chromium.org>
Change-Id: I046ae18c9db9a5d682384edde303c07e0be9d790
Reviewed-on: https://review.coreboot.org/c/coreboot/+/54146
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
4 files changed
tree: efe8ff943d0939e2b466e594e04b5c2282081b94
  1. 3rdparty/
  2. configs/
  3. Documentation/
  4. LICENSES/
  5. payloads/
  6. src/
  7. tests/
  8. util/
  9. .checkpatch.conf
  10. .clang-format
  11. .editorconfig
  12. .gitignore
  13. .gitmodules
  14. .gitreview
  15. AUTHORS
  16. COPYING
  17. gnat.adc
  18. MAINTAINERS
  19. Makefile
  20. Makefile.inc
  21. README.md
  22. toolchain.inc
README.md

coreboot README

coreboot is a Free Software project aimed at replacing the proprietary BIOS (firmware) found in most computers. coreboot performs a little bit of hardware initialization and then executes additional boot logic, called a payload.

With the separation of hardware initialization and later boot logic, coreboot can scale from specialized applications that run directly firmware, run operating systems in flash, load custom bootloaders, or implement firmware standards, like PC BIOS services or UEFI. This allows for systems to only include the features necessary in the target application, reducing the amount of code and flash space required.

coreboot was formerly known as LinuxBIOS.

Payloads

After the basic initialization of the hardware has been performed, any desired "payload" can be started by coreboot.

See https://www.coreboot.org/Payloads for a list of supported payloads.

Supported Hardware

coreboot supports a wide range of chipsets, devices, and mainboards.

For details please consult:

Build Requirements

  • make
  • gcc / g++ Because Linux distribution compilers tend to use lots of patches. coreboot does lots of "unusual" things in its build system, some of which break due to those patches, sometimes by gcc aborting, sometimes - and that's worse - by generating broken object code. Two options: use our toolchain (eg. make crosstools-i386) or enable the ANY_TOOLCHAIN Kconfig option if you're feeling lucky (no support in this case).
  • iasl (for targets with ACPI support)
  • pkg-config
  • libssl-dev (openssl)

Optional:

  • doxygen (for generating/viewing documentation)
  • gdb (for better debugging facilities on some targets)
  • ncurses (for make menuconfig and make nconfig)
  • flex and bison (for regenerating parsers)

Building coreboot

Please consult https://www.coreboot.org/Build_HOWTO for details.

Testing coreboot Without Modifying Your Hardware

If you want to test coreboot without any risks before you really decide to use it on your hardware, you can use the QEMU system emulator to run coreboot virtually in QEMU.

Please see https://www.coreboot.org/QEMU for details.

Website and Mailing List

Further details on the project, a FAQ, many HOWTOs, news, development guidelines and more can be found on the coreboot website:

https://www.coreboot.org

You can contact us directly on the coreboot mailing list:

https://www.coreboot.org/Mailinglist

Copyright and License

The copyright on coreboot is owned by quite a large number of individual developers and companies. Please check the individual source files for details.

coreboot is licensed under the terms of the GNU General Public License (GPL). Some files are licensed under the "GPL (version 2, or any later version)", and some files are licensed under the "GPL, version 2". For some parts, which were derived from other projects, other (GPL-compatible) licenses may apply. Please check the individual source files for details.

This makes the resulting coreboot images licensed under the GPL, version 2.