[Qemu-devel] Re: [PATCH 2/3] char: Remove special init_reset handling

[Amit Shah]

On (Wed) Nov 04 2009 [10:39:39], Jan Kiszka wrote:
> Amit Shah wrote:
> > On (Tue) Nov 03 2009 [19:53:43], Jan Kiszka wrote:
> >> Amit Shah wrote:
> >>> On (Tue) Nov 03 2009 [23:25:52], Amit Shah wrote:
> >>>> On (Tue) Nov 03 2009 [18:08:57], Jan Kiszka wrote:
> >>>>> Amit Shah wrote:
> >>>>>> The initial_reset sent to chardevs doesn't do much other than setting
> >>>>>> a bool to true. Char devices are interested in the open event and
> >>>>>> that gets sent whenever the device is opened.
> >>>>> Have you checked with the monitor in all use cases (dedicated & muxed
> >>>>> console, stdio & SDL console, etc.)? It was introduced once to fix a
> >>>> I've checked with -monitor stdio, monitor in SDL and also chardevs using
> >>>> unix sockets.
> >>>>
> >>>> I've not tried mux yet; I'll try that and report back. BTW if it ends up
> >>>> not working with this patch, it'd be broken in the current master as
> >>>> well.
> >>> I tried with:
> >>>
> >>> -chardev stdio,mux=on,id=mux -monitor chardev:mux -serial chardev:mux
> >>>
> >>> The monitor prompt shows up as does the serial output.
> >>>
> >>> (btw I've also tried closing and opening char devs and that works fine
> >>> too)
> >> That sounds good. Then something must have changed since 2970a6c943, do
> >> you see what?
> > 
> > I think that depended on the resets being sent. I've now removed the
> > need for resets altogether.
> 
> No, this is in fact the reason why we no longer need it:
> 
>       9a1e948129 (Introduce contexts for asynchronous callbacks)
> 
> As the initial reset of the char device that is marked pending on open
> is now no longer consumed by the IDE initialization, we can actually
> drop the later regeneration via qemu_chr_initial_reset. I just hope this
> stays like it is...

I tested this even on a tree that doesn't have this patch.

I haven't really delved deep to see why this was added earlier -- the
commit log only says very little. Plus my testing with the current tree
works fine so I'm happy to mention these things in the commit log.

                Amit