Question

I already did the hard part of adding a system call to the linux kernel. I need to return the following array:
unsigned int counts[4]
I can reference the array as curr->counts, but I don’t think there is a return value for that, and I think it is bad to give a pointer into kernel space?
Instead I’m thinking the best way is to return void and pass by parameter. Is that the way to go?

Answer 1

See the kernel routine copy_to_user (). Design the system call interface to pass a parameter which is a pointer where to return the data.

You are trying to do something like the read() or gettimeofday() system calls, right? Those all return more than 32-bit results by using copy_to_user().