tree d9d8751eebc7e96076678aa04dd9a12d9a5552d2
parent ab496bf1770b4b2a1b0f6a99e14e736c43190b44
author Lean Sheng Tan <sheng.tan@9elements.com> 1678890721 +0100
committer Lean Sheng Tan <sheng.tan@9elements.com> 1681569389 +0000

soc/intel/alderlake: Enable early caching of RAMTOP region

Enable early caching of the TOM region to optimize the boot time by
selecting `SOC_INTEL_COMMON_BASECODE_RAMTOP` config.

Purpose of this feature is to cache the TOM (with a fixed size of
16MB) for all consecutive boots even before calling into the FSP.
Otherwise, this range remains un-cached until postcar boot stage
updates the MTRR programming. FSP-M and late romstage uses this
uncached TOM range for various purposes (like relocating services
between SPI mapped cached memory to DRAM based uncache memory) hence
having the ability to cache this range beforehand would help to
optimize the boot time (more than 50ms as applicable).

TEST=Able to build and boot Starlab ADL laptop to OS.

Signed-off-by: Lean Sheng Tan <sheng.tan@9elements.com>
Change-Id: Iba554af4ff0896e133d20860ff72dd1a10ebd1e3
Reviewed-on: https://review.coreboot.org/c/coreboot/+/73736
Reviewed-by: Subrata Banik <subratabanik@google.com>
Reviewed-by: Sean Rhodes <sean@starlabs.systems>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Maximilian Brune <maximilian.brune@9elements.com>