PDF at http://am.lcs.mit.edu/~rsc/xv6.pdf

Various changes made while offline.

 + bwrite sector argument is redundant; use b->sector.
 + reformatting of files for nicer PDF page breaks
 + distinguish between locked, unlocked inodes in type signatures
 + change FD_FILE to FD_INODE
 + move userinit (nee proc0init) to proc.c
 + move ROOTDEV to param.h
 + always parenthesize sizeof argument

delete unused functions
a few comments

fix bug in test code of malloc

cd in shell
nits in mkdir, ls, etc.

proc[0] calls iget(rootdev, 1) before forking init

each cpu[] has its own gdt and tss
no per-proc gdt or tss, re-write cpu's in scheduler (you win, cliff)
main0() switches to cpu[0].mpstack

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

fix acquire() to cli() *before* incrementing nlock
make T_SYSCALL a trap gate, not an interrupt gate
sadly, various crashes if you hold down a keyboard key...

give cpu1 a TSS and gdt for when it enters scheduler()
and a pseudo proc[] entry for each cpu
cpu0 waits for each other cpu to start up
read() for files

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

New scheduler.

Removed cli and sti stack in favor of tracking
number of locks held on each CPU and explicit
conditionals in spinlock.c.