Board:lenovo/x200/internal flashing research

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Introduction

The goal is to be able to flash internally the x200 with Flashrom.

Anti-reflashing mechanisms

The Lenovo X200 uses the following mechanisms to prevent internal reflashing:

  • Flash descriptor: Set the flash descriptor read-only, locks the ME, and platform regions.
  • PR registers: Sets the BIOS bootblock read-only and prevent access to the platform region

Idea

The flash descriptor restrictions can be lifted by using the GPIO33. That would then permit us, once booted, to reflash all the flash chip but what is still covered by the PR registers. This should be enough to relocate coreboot/libreboot outside of the region covered by the PR registers.

Since the platform region would still be locked by the PR registers, flashrom will need to be patched not to touch it at all (it should not even try to read it).