# 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!