RE: specific item names in config files

Question

Under a previous question 'Does Ubuntu use security features like DEP and ALSR' it was mentioned "if you aren't running a PAE kernel, or your hardware lacks the NX bit, Ubuntu emulates the NX feature". I wish to reconfigure kernel to delete (not disable) this ability to emulate the NX feature. What are the specific item names in config files I need to erase?

Answer 1

I really can't imagine why you want to do this, you are exposing your hardware and software to a big threat that you can control at runtime if you compile a new kernel as you would.

However, instead of naming all the options, make things smarter and run a

make xconfig

in the root folder where the source of the kernel is, this will make a window shows up where you can set all the options for your .config file. Go in

Edit > Find

and search for highmem, this options are not strictly related to the NX bit but with memory management in general and with the PAE feature, usually the developers are just interested in setting HIGHMEM64G to y to get a kernel that is PAE enabled.

Talking about an "NX bit only" feature, there is the symbol DEBUG_NX_TEST.

Also, you have to play with your bootloader, for example https://bbs.archlinux.org/viewtopic.php?id=39044 .

My advice is, play with highmem options as much as you want, but just consider options like the NX bit off limits, because you can loose the control of your machine in less than a fraction of second and you can't control memory mapping in realtime, you are not a machine.