Previously, deallocuvm scanned from 0 to KERNBASE in one page
increments, which had a noticable effect on boot time.  Now it skips
over missing page directories.

exec() with arguments that don't fit on a single page.

Switch back to #define for PHYSTOP.  Using the E820 to retrieve the memory map is too complicated (must be done in 16-bit real-mode, probably enlarged bootblock beyond 512 bytes, and a #define requires less explanation).

Get rid of last instances of linear address and "la"
Get ready for detecting physical memory dynamically

2011

Remove device mapping from bootpgdir
Remove unnecessary vmenable
Set CPUS back to 2 in Makefile
Passes all usertests

Allocate proper kernel page table immediately in main using boot allocator
Remove pginit
Simplify address space layout a tiny bit
More to come (e.g., superpages to simplify static table)

All tests pass

Passes all tests now (but need to update usertests to allow for more than 640k)

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.

usertest that passes too many arguments, break exec

delete most comments from bootother.S (since copy of bootasm.S)
ksegment() -> seginit()
move more stuff from main() to mainc()

Simplify allocuvm/deallocuvm to operate in a contiguous memory model.  This makes their interface match up better with proc->sz and also simplifies the callers (it even gets the main body of exec on one page).

Rearrange vm.c so it's in logical order and prints nicely.  Shorten a few functions in uninteresting ways to make them fit.

Slight simplification of copyuvm.  We could simplify other things now that processes are contiguous, but we'd have to think harder about the error paths.