Our proc.c alignment is perfect.  Since ksegment/usegment went away, we get a column back, so we get our two action-packed spreads.

Swap bootmain.c and bootother.S.  This puts the whole boot process on one spread, though it separates the two asm files.

We don't use lesp/lebp and using them at all from C would be fraught with peril.  Keep resp/rebp, but fix their code style.

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

Fix for gdbstub argument change in qemu 0.11.  Rename qemu-gdb-nox target to qemu-nox-gdb because you frequently want to add the gdb part, but rarely the nox part.

increase PHYSTOP

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

find out the hard way why user and kernel must have separate segment descriptors