Re: [Qemu-devel] [RFC] [PATCHv6 01/16] aio / timers: add qemu-timer.c utility functions

[Stefan Hajnoczi]

On Tue, Aug 06, 2013 at 01:30:18PM +0100, Alex Bligh wrote:
> --On 6 August 2013 14:02:18 +0200 Stefan Hajnoczi
> <address@hidden> wrote:
> My preference would be to move these to qemu_clock_deadline_ns (without
> the INT32_MAX check) and delete the old qemu_clock_deadline routine
> entirely, but I don't really understand the full set of circumstances
> in which the qtest routines are meant to work.

Okay, that's excellent.  It would be great to move to a single function.

The way qtest works is that it executes QEMU in a mode that does not run
guest code.  Instead of running guest code it listens for commands over
a socket.  The wire protocol can peek/poke memory, notify of interrupts,
and warp the clock.

There are test cases that use qtest to test emulated devices.

When qtest either steps the clock or sets it to a completely new value
using qtest_clock_warp() it runs all vm_clock timers that should expire
before the new time.

Does this help?

> >Please include
> >an explanation of why qemu_timeout_ns_to_ms() will be needed in the
> >future (there are no callers in this patch).
> 
> You mean in the commit text as well as the following?
> 
> +/* Transition function to convert a nanosecond timeout to ms
> + * This is used where a system does not support ppoll
> + */

Usually a doc comment is enough since it explains what the function
does.  If it's a low-level function is may be necessary to give more
context in the commit description.

Stefan