f00f: We don't need giant to manipulate vm structures

[imp]

Summary

We don't need to assert we have Giant here. The VM subsystem
has been Giant free for some time now.

Sponsored by: Netflix

[kib]

This does not have anything to do with VM.

[imp]

In D31839#718224, @kib wrote:

This does not have anything to do with VM.

What's the right low level term for the pmap and IDT fiddling it does then?

[kib]

In D31839#718395, @imp wrote:

In D31839#718224, @kib wrote:

This does not have anything to do with VM.

What's the right low level term for the pmap and IDT fiddling it does then?

It is part of the cpu setup code. Actually it is safe to do this manipulation there because

1. all machines where it matters are UP
2. interrupts are disabled

These are the guarantees that this code needs to work.

pmap_trm_alloc() allocates memory in the trampoline area which is shared between kernel and userspace. After 4/4 UVA/KVA split was implemented, kernel no longer shares (whole) address space with userspace on i386.