Re: [Qemu-devel] [PATCH] versatile: Push lsi initialization to the end

[Paolo Bonzini <pbonzini@redhat.com>]

Il 08/10/2012 08:52, Jan Kiszka ha scritto:
> On 2012-10-06 04:13, Peter Maydell wrote:
>> On 5 October 2012 19:01, Jan Kiszka <jan.kiszka@siemens.com> wrote:
>>> I'm not a fan of this either, but the alternatives are way more
>>> complicated. We either need to rewrite the chardev subsystem,
>>> specifically how mux'ed devices are registered and how the active one is
>>> selected. Or we need to avoid flushing "unrelated" BHs for block
>>> devices. Not sure of those read requests can be postponed.
>>
>> Is this a regression? If it is then the obvious answer is to back
>> out whatever broke it...
> 
> I'm using this machine for the first time, so I cannot answer this from
> the top of my head. However, I don't think it can be a regression.
> 
> Mux chardevs work like this: You create the backend, then you register
> the frontend with them, one by one. The last one registered is the first
> one active. It should also receive the open event of chardev. But as
> that open even is issued via a BH and last frontend, the serial device,
> arrives after the first BH flushing, things break.

Does something like this work instead?

diff --git a/qemu-char.c b/qemu-char.c
index b082bae..1ed6d49 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -465,6 +465,9 @@ static void
mux_chr_update_read_handler(CharDriverState *chr)
     d->focus = d->mux_cnt;
     d->mux_cnt++;
     mux_chr_send_event(d, d->focus, CHR_EVENT_MUX_IN);
+    if (chr->opened) {
+        mux_chr_send_event(d, d->focus, CHR_EVENT_OPENED);
+    }
 }

 static CharDriverState *qemu_chr_open_mux(CharDriverState *drv)

Paolo