Very important to give qemu memory through PHYSTOP :(

Variable declarations at top of function,
separate from initialization.

Use == 0 instead of ! for checking pointers.

Consistent spacing around {, *, casts.

Declare 0-parameter functions as (void) not ().

Integer valued functions return -1 on failure, 0 on success.

do not keep sorted contiguous free list

put an invalid page below the stack
have fork() handle invalid pages

fix corner cases with alignment when mapping kernel ELF file

(maybe this never worked, but it works now)

 * rename c/cp to cpu/proc
 * rename cpu.context to cpu.scheduler
 * fix some comments
 * formatting for printout

so fast interrupts overflow the kernel stack
fix: cli() before lapic_eoi()

iget
mkfs makes a file system image
put this in your .bochsrc:
ata0-slave: type=disk, mode=flat, path="fs.img", cylinders=1024, heads=1, spt=1

Eliminate annoying Pseudodesc structure.
Eliminate unnecessary parts of mmu.h.