Goswin von Brederlow wrote:
The question is wether linux supports it too in that mode. It has to remap the 64bit page tables into the strange 64GB address setup.
I think you're still confusing things here.When a x86_64 process is not in long-mode (i.e., 64-bit virtual addressing), it is a IA-32 processor. That includes supporting PAE. There is no 64-bit remapping to be done, because the PTEs are still 32bits.
Whne it's in long mode (i.e., 64-bit virtual addressing), it has 48bits of physical addressing space to begin with. That totally precludes the need for PAE, so it doesn't need it.
Remember, PAE is a physical addressing trick, to allow mapping of 32-bit virtual addresses to a 36-bit physical address space.
In long mode, such tricks aren't needed, as the addressing is 64-bit virtual and 48-bit physical.
It does. Because you wouldn't be booting a x86_64 kernel, but a plain x86 one.IF. That is the big question.
Adam