Intr

See merge request projectn/nemu!10

device,vga: add macro SHOW_SCREEN

See merge request projectn/nemu!9

Fix rv64 muldiv

See merge request projectn/nemu!8

main: return 0 only when hitting good trap

See merge request projectn/nemu!7

* other scripts can report an error when NEMU does not return
  successfully

monitor,diff-test: add port to QEMU

See merge request projectn/nemu!6

* now different instances can connect to QEMU via different ports

Fix difftest

See merge request projectn/nemu!5

* If we put mainargs at a device, x86 may directly use it to perform
  computation, such as cmp (%eax), 0, where %eax points to the device.
  But the monitor will skip every instruction accessing device, which
  makes REF skip generating correct EFLAGS.
* Putting mainargs at RAM solves this issue.

Rv64 cte

See merge request projectn/nemu!4

* the LSB of funct7 may be "1" due to the shift amount can be >= 32

* the src should be first sign-extended

* Now we can run PAL over Nanos-lite, but it gets stuck while battling.
  It seems mul/div instructions are wrong.

Fix isa64

See merge request projectn/nemu!3