Add a new system call called trace to xv$6.$ Its syntax is

int trace$($int$)$

When called with a non$-$zero parameter, e$.$g$.,$ trace$(1),$ system call tracing is

turned on for that process. Each system call from that process will be printed to

the console in a user$-$friendly format showing:

$$ the process ID

$$ the process name

$$ the system call number

$$ the system call name

Any other processes will not have their system calls printed unless they also call

trace$(1).$

Calling trace$(0)$ turns tracing off for that process. System calls will no longer be

printed to the console.

In all cases, the trace system call also returns the total number of system calls

that the process has made. Hence, you can write code such as:

printf$("$total system calls so far $=\%$d

$",$ trace$(0))$;

The system call counting for each system call on a per$-$process basis. You will

need to keep track of this in the process control block, the proc structure.

Write a test program $($try$.$c$)$ to test your trace system call