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.

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

pdf has very good page breaks now.
would be a good copy for fall 2009.

group locks into structs they protect.
few naming nits.

Delete parallel port output.
Works well with qemu -nographic mode.

Change dev read/write functions
to take inode* instead of minor number.

Unlock console inode during console_read
and console_write.  Otherwise background
processes cannot write to console while the
shell is reading it waiting for input.

if no lapic available, use 8253pit for clock
now xv6 runs both on qemu (uniprocessor) and bochs (uniprocessor and MP)