The funny page table terminology on AMD64
What’s the next word in this sequence: PT, PD, PDP, …?
Michael Steil
Asking the kernel how to make a syscall
Imagine you’re an i386 user mode application on a modern operating system, and you want to make a syscall, for example to request some memory or create a new thread. But syscalls can be made in various ways on the i386 family of CPUs (int, call gates, sysenter, syscall), and CPUs tend to support only a subset of them. But hardcoding “int” into the kernel is a waste of resources on modern CPUs, because sysenter is a lot faster.
Why does PUSHA also push the stack pointer?
This puzzle is actually a quite easy one – but when I asked it in a university course, it kept some people busy for some time to find out the answer, so I thought it might be a good idea to ask you nevertheless:
How NOP nearly became a non-NOP on AMD64
AMD64 is a quite clean extension of the i386 instruction set, it obsoletes many rarely used features of the i386 and introduces new registers, making the instruction set a lot more… logical.