To PSE or not to PSE, that's the question

[TopSekret]

As you probably all know, adding support for more paging schemas (486, PSE, PSE-36, PAE, 4L) is hours of work.

My question is: is having PSE support (after having PSE, PSE-36 is very simple) worth a few hours?

Pros:

• Support for 4MB pages (PAE has only 2MB)
• The same structures as 486 paging
• Strips one layer of Page Lookup = faster

Cons:

• No NX bit
• PSE-36 is a piece of sh**

[madanra]

Personally, I'd stick to 64-bit, where the decision is made for you.

[Octocontrabass]

Pros:

• PSE might be faster than PAE (thanks to larger pages and smaller page tables)
• Some (very old?) CPUs support PSE but not PAE

Cons:

• PSE might be slower than PAE (it's probably not an optimization target for Intel or AMD)
• Accessing memory above 4GB requires PSE-36
• PSE-36 might be slower than PAE (since you can't use 4kB pages above 4GB)
• Some (very old?) CPUs support PAE but not PSE-36
• NX/XD requires PAE

If you're specifically targeting non-PAE hardware, it might be worthwhile to support PSE (but not PSE-36); otherwise, stick to PAE or switch to 64-bit.

[Ch4ozz]

Hm, I'd consider using PAE for the NX bit only, if your looking for more RAM covering you should simply move to long mode
PSE sounds like a feature nobody would even expect from an OS since PAE and 64 bit were designed