coreboot-libre-fam15h-rdimm/Documentation/arch/x86/pae.md

x86_32 PAE documentation

Due to missing x86_64 support it's required to use PAE enabled x86_32 code. The corresponding functions can be found in src/cpu/x86/pae/.

Memory clearing helper functions

To clear all DRAM on request of the Security API, a helper function can be used called memset_pae. The function has additional requirements in contrast to memset, and has more overhead as it uses virtual memory to access memory above 4GiB. Memory is cleared in 2MiB chunks, which might take a while.

Make sure to enable caches through MTRRs, otherwise memset_pae will be slow!