set compiler toolchain and qemu exec
notes and fix typo
use i386 qemu; comments on boot.S:GDT and segment desc
exec 8: add %o to printf
comment on _start and entry addresses
gitignore
indent all sources
indenting console.c
exec 10: backtrace
exec 12: backtrace. XXX: line number is always 0???
disable -O1
all execsices complete, grade should all passed, 30/50 makes no sense
merge updates from lab1
indent
comment memory layout
exec 1: done. mem_init() and page_init() works
exec4: after hours of testing (without gdb), it passed all assertions.
exec 5: all success. just call APIs, also fixed a bug in previous exec.
answering questions in lab2
challenge-1: use page size extension (4MB page-size), done. improved check_va2pa() to handle 4MB page-size