Re: [Qemu-devel] [PATCH 3/8] RunState: Add additional states

[Luiz Capitulino]

On Thu, 01 Sep 2011 22:58:51 +0200
Jan Kiszka <address@hidden> wrote:

> On 2011-09-01 20:39, Luiz Capitulino wrote:
> > On Thu, 01 Sep 2011 20:30:57 +0200
> > Jan Kiszka <address@hidden> wrote:
> > 
> >> On 2011-09-01 20:12, Luiz Capitulino wrote:
> >>> Currently, only vm_start() and vm_stop() change the VM state.
> >>> That's, the state is only changed when starting or stopping the VM.
> >>>
> >>> This commit adds the runstate_set() function, which makes it possible
> >>> to also do state transitions when the VM is stopped or running.
> >>>
> >>> Additional states are also added and the current state is stored.
> >>>
> >>> Signed-off-by: Luiz Capitulino <address@hidden>
> >>> ---
> >>>  cpus.c      |    1 +
> >>>  migration.c |    8 +++++++-
> >>>  sysemu.h    |   10 +++++++++-
> >>>  vl.c        |   20 ++++++++++++++++++++
> >>>  4 files changed, 37 insertions(+), 2 deletions(-)
> >>>
> >>
> >> ...
> >>
> >>> diff --git a/vl.c b/vl.c
> >>> index f0b56a4..59f71fc 100644
> >>> --- a/vl.c
> >>> +++ b/vl.c
> >>> @@ -321,6 +321,22 @@ static int default_driver_check(QemuOpts *opts, void 
> >>> *opaque)
> >>>  }
> >>>  
> >>>  /***********************************************************/
> >>> +/* QEMU state */
> >>> +
> >>> +static RunState current_run_state = RSTATE_NO_STATE;
> >>> +
> >>> +bool runstate_check(RunState state)
> >>> +{
> >>> +    return current_run_state == state;
> >>> +}
> >>> +
> >>> +void runstate_set(RunState state)
> >>> +{
> >>> +    assert(state < RSTATE_MAX);
> >>> +    current_run_state = state;
> >>
> >> I still think this should check for valid state transitions instead of
> >> blindly accepting what the caller passes in.
> > 
> > I thought your comment where more like a future enhancement than
> > a request for change.
> 
> I think we want this now to document at a central place which
> transitions are valid and which not. State machines without such checks
> break sooner or later, subtly.

Ok, I'll do it.

Do you have any suggestion on the preferred way to document it?
Should I use english or try some ascii art?

> 
> > 
> > What to do if the transition is invalid? abort()?
> 
> Yes.
> 
> Jan
>