can I get cr3's value like this?

[junior_study]

hi:

       this instruction   ?   movl  %cr3  ,  %eax   
       can  this indtruction  load  cr3's value into  eax?

thank you!

[Frank Kotler]

No, not in Nasm syntax. Try:

Code: [Select]

mov eax, cr3
... and not in user mode in a protected OS. A "mov" into or out of a control register is a "privileged instruction" - won't work in ring 3. From "real real-mode dos" (or "write my own OS mode", yes. Probably not meaningful until you've loaded something into it... and not effective until you've enabled paging (bit 31 in cr0, I think). Possibly in a kernel module...

You probably want to study the Intel/AMD manual(s), and/or http://www.sandpile.org and/or http://www.osdev.org More of a "senior study", I think.

Best,
Frank