Presumably because of the pre-loaded file system, the default RAM is
insufficient when running kernelmemfs

Commit 9aa0337d introduced a linker script for linking the kernel image,
but only changed the kernel target to use it.  kernelmemfs was still
using the old linker command line arguments, which weren't sufficient.

But check that mkfs.c is building with LP64

Maybe the string boot shouldn't appear in xv6 code?

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)

Maybe not necessary, but don't want to waste time figuring this out again

Very important to give qemu memory through PHYSTOP :(

Passes usertests and stressfs
Seems to recover correctly in a number of simple cases

At some point between gcc 4.4 and 4.6, omitting the frame pointer
became default if any -O is specified.  getcallerpcs relies on the
frame pointer, so bring it back.

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.

(maybe this never worked, but it works now)

locks were moved around.