PA -- A new journey for the OS
This blog will begin from the half of PA1 Because I thought "STFW" can solve the problems before. I have to confirm that I have install the Ubuntu 22.04 for my CS task, so I look through the PA0 in a fast way.
PA1 The simplest computer
infrastructure
There always exist infrastructure where exist codes.
The course build a significant infrainstructure called Simple Debugger(sdb) in the NEMU.
NEMU is regarded as a programm to excute other guest programm which means NEMU can know all information of the guest programm.
However, the information is hard to be caught by the debugger out of the NEMU, such as GDB.(set a breakpoint by GDB for the guest programm is also hard)
Inorder to improve the efficiency of debugging, we need to build a simple Debugger at the monitor.
Below are the format and functions:
| instruction | format | example | explanation |
|---|---|---|---|
| help | help | help | print help of instructions |
| continue | c | c | continue to run the programm is suspended |
| quit | q | q | quit NEMU |
| run by step | si [N] | si 10 | run N instructions by step then stop, default N is equal to 1 |
| print program status | info SUBCMD | info rinfo w | print register status print monitor message |
| scale Memory | x N EXPR | x 10 $esp | figure out the value of EXPR and set it as the begining of the Memory. output N*4 bytes as hex format |
| figure out the expression value | p EXPR | p $eax + 1 | figure out EXPR value |
| set monitor | w EXPR | w *0x2000 | when EXPR changes, suspend the program |
| delete monitor | d N | d 2 | delete monitor whose label is N |