overview.rst 3.6 KB

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  1. .. SPDX-License-Identifier: GPL-2.0+
  2. .. Copyright 2020 Google LLC
  3. Chromium OS Support in U-Boot
  4. =============================
  5. Introduction
  6. ------------
  7. This describes how to use U-Boot with Chromium OS. Several options are
  8. available:
  9. - Running U-Boot from the 'altfw' feature, which is available on selected
  10. Chromebooks from 2019 onwards (initially Grunt). Press '1' from the
  11. developer-mode screen to get into U-Boot. See here for details:
  12. https://chromium.googlesource.com/chromiumos/docs/+/HEAD/developer_mode.md
  13. - Running U-Boot from the disk partition. This involves signing U-Boot and
  14. placing it on the disk, for booting as a 'kernel'. See
  15. :doc:`chainload` for information on this. This is the only
  16. option on non-U-Boot Chromebooks from 2013 to 2018 and is somewhat
  17. more involved.
  18. - Running U-Boot with Chromium OS verified boot. This allows U-Boot to be
  19. used instead of either or both of depthcharge (a bootloader which forked
  20. from U-Boot in 2013) and coreboot. See :doc:`run_vboot` for more
  21. information on this.
  22. - Running U-Boot from coreboot. This allows U-Boot to run on more devices
  23. since many of them only support coreboot as the bootloader and have
  24. no bare-metal support in U-Boot. For this, use the 'coreboot' target.
  25. - Running U-Boot and booting into a Chrome OS image, but without verified
  26. boot. This can be useful for testing.
  27. Talks and documents
  28. -------------------
  29. Here is some material relevant to Chromium OS verified boot with U-Boot:
  30. - "U-Boot with Chrome OS and firmware packaging"
  31. - Author: Simon Glass
  32. - Presented at Open Source Firmware Conference 2018, Erlangen
  33. - Describes the work in progress as at the end of 2018
  34. - Slides at `OSFC <https://2018.osfc.io/uploads/talk/paper/26/U-Boot_with_Chrome_OS_and_firmware_packaging.pdf>`_
  35. - `Youtube video 'OSFC - U-Boot with Chrome OS and firmware packaging' <https://www.youtube.com/watch?v=1jknxUvmwpo>`_
  36. - "Verified Boot in Chrome OS and how to make it work for you"
  37. - Author: Simon Glass
  38. - Presented at ELCE 2013, Edinburgh
  39. - Describes the original 2013 implementation as shipped on snow (first
  40. `ARM Chromebook was a Samsung Chromebook <https://www.cnet.com/products/samsung-series-3-chromebook-xe303c12-11-6-exynos-5250-2-gb-ram-16-gb-ssd-bilingual-english-french/>`_
  41. with Samsung Exynos5250 `review <https://www.cnet.com/reviews/samsung-chromebook-series-3-review/>`_),
  42. spring (`HP Chromebook 11 <https://www.cnet.com/products/hp-chromebook-11-g2-11-6-exynos-5250-4-gb-ram-16-gb-emmc/>`_)
  43. and pit/pi (`Samsung Chromebook 2 <https://www.cnet.com/products/samsung-chromebook-2-xe503c12-11-6-exynos-5-octa-4-gb-ram-16-gb-ssd/>`_
  44. with Exynos 5 Octa 5420 in 2014).
  45. - Slides at `Google research <https://research.google/pubs/pub42038/>`_
  46. - `Youtube video 'Verified Boot on Chrome OS and How to do it yourself' <https://www.youtube.com/watch?v=kdpZC9jFzZA>`_
  47. - "Chrome University 2018: Chrome OS Firmware and Verified Boot 201"
  48. - Author: Duncan Laurie
  49. - Describes Chrome OS firmware as of 2018 and includes a wide range of
  50. topics. This has no U-Boot information, but does cover coreboot and also
  51. talks about the Chrome OS EC and Security chip. This is probably the
  52. best introduction talk.
  53. - `Youtube video 'Chrome University 2018: Chrome OS Firmware and Verified Boot 201' <https://www.youtube.com/watch?v=WY2sWpuda2g>`_
  54. - `Chromium OS U-Boot <https://www.chromium.org/developers/u-boot>`_
  55. - `Firmware porting Guide <https://www.chromium.org/chromium-os/firmware-porting-guide>`_