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

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)

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.

kinit() knows about end and PHYSTOP
map all of kernel read/write (rather than r/o instructions)
thanks, austin

do not keep sorted contiguous free list

increase PHYSTOP

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

passes all tests on two-processor smp

group locks into structs they protect.
few naming nits.

nits in comments

lots of cleanup

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