Strace 4 Linux x86 - IO traceing

[Roland McGrath]

This is not something that is really apropos to strace, or at least not in
the current circumstances.  strace uses the operating system's facilities
for catching a process doing a system call.  You would need an equivalent
facility in the operating system, i.e. the Linux kernel.  As far as I know,
there is no aspect of the ptrace facility that lets you trap io instructions.
>From my understanding of the x86 hardware facilities, it would have to work
by disallowing the permissions that ioperm/iopl enable, catching the fault,
and then handling it specially.  Not real hard to do, but it has to be done
before strace can consider supporting it.