1. virtio_blk
  comment debug log

1. fat32
  remove bufferIO related log

1. fat32
  use LRU in buffered IO

2. utils
  add sum utils

3. kmem
  add slab obj with size == 2048, the max is 2048( was 1024)

1. fat32
  reading file works

2. earlylog
  add puts function because printf has a buffer size limit

1. fat32
  add prelimiary support for getting file names in directory

2. kustd
  add heper function, strcpy_end, which returns the pointer pointing to
  null char

3. gdbinit.py
  using extended-remote

1. Makefile
  add more qemu log

1. hal
  add hal.

1. virtio_blk
  fix a return value bug. virtio_blk_wait.

1. fat32
  add simple buffered IO

1. virtio virtio_blk
  add return value for virtio_blk_wait

1. virtio virtio_blk
  fix bug about RING_EVENT_IDX

1. CMakeLists
  add hal directory

2. fat32
  add fat32.c fat32.h

3. hal
  add disk_hal.c disk_hal.h as a hal of disk which would be backed with virtio_blk of QEMU or sdcard on K210

4. virtio_blk
  improvement on virtio_blk_wait

merge virtio branch into dev.

1. virtio virtio_blk
  works with complete interface.

1. main.c
  enable paging in hart 1

2. sbi.c
  supress trivial warning.

1. .gitignore
  add *.log

2. main.c
  fix bug about kpte

3. Makefile
  add qemu log

add spinlock and muticore start

Revert #1 

1. virtio virtio_blk
  add a more firendly interface

2. utils
  add align_next

Merge #1 from ZonePG/dev

add spinlock_t and muit-core startup support.

1. earlylog.c
  change spinlock for printf
2. entry.s main.c
  add startup_stack2 for hart 2

1. vritio_blk
  read disk successfully, next step is to organize the code.

1. linker.ld
  change the secionts position

2. kvm.c
  map all secionts with PTE_XWR_SET

1. kvm.c
  add virtio-blk map

1. Makefile
  add qemu options, to disable virtio-blk legacy

2. virtio
  basic defs

3. kustd
  fix memcpy and memmove

1. spinlock.c spinlock.h
  add spinlock
2. earlylog.c earlylog.h
  add spinlock for printf
3. main.c
  change muticore call printf for spinlock

1. CMakeLists.txt
  add QEMU and K210 macro which are passed to gcc

2. Makefile
  add QEMU and K210 args passed to CMakeLists

1. main.c sbi.h
  add muticore start

2. gdbinit.py
  change display src and asm window

1. entry.s
  bug fix about stack address

2. swtch.s
  add swtch funtion

1. riscv
  functions to read write set and clear specifed csr
2. kvec
  kernel interrupt handler works now.
3. timer interrupt
  it works now.