Description:

This repository is forked from https://github.com/mit-pdos/xv6-public As part of an assignment to add a trace syscall to xv6.

How to execute / test:

This adds a trace system call to xv6, which enables/disables verbose output of every system call made and its return value.

int trace(int)

The argument can be T_UNTRACE, which unsets tracing, or T_TRACE which sets tracing, or T_TRACE | T_ONFORK which sets tracing for current process and also any child created using fork.

we have a test program trd which just runs some syscalls to confirm.

We can also enable or disable tracing from shell itself. trace command enables syscall printing for any command invoked from shell. untrace disables it.

To see changes from original xv6 code:

git diff eeb7b415dbcb12cc362d0783e41c3d1f44066b17 .

(here the long checksum indicates last commit in xv6 original code, you can see the log by running git log)

I have committed all changes at once because commit history was noise.

Bugs

If you find any bug or unhandled edge case, fill an issue.