1# x86_32 PAE documentation 2 3Due to missing x86_64 support it's required to use PAE enabled x86_32 code. 4The corresponding functions can be found in ``src/cpu/x86/pae/``. 5 6## Memory clearing helper functions 7 8To clear all DRAM on request of the 9[Security API](../../security/memory_clearing.md), a helper function can be used 10called `memset_pae`. 11The function has additional requirements in contrast to `memset`, and has more 12overhead as it uses virtual memory to access memory above 4GiB. 13Memory is cleared in 2MiB chunks, which might take a while. 14 15Make sure to enable caches through MTRRs, otherwise `memset_pae` will be slow! 16