PSE and PAE in long mode

[lopidas]

Does PSE bit in cr4 have any effect in 64-bit or compatibility sub-mode long mode?

I have seen many tutorials saying that PAE must be enabled before entering long mode and that PAE scheme is default for long mode. What will happen, if I will enable long mode without PAE?

[lopidas]

I found that, AMD64 manual says that enabling long mode without PAE results into #GP and another that trying to use bigger address than 32-bit.

[feryno]

yes enable PAE and forget about CR4.PSE (CR4.PSE is not used in long mode)
in long mode you can use PSE bit of paging tables to make 2 MB pages (3-level) instead of 4 kB (4 levels) - or even 1 GB pages (2-level translation) on newer CPUs - usually server models