From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:34473) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TLFGF-0004Vk-3w for qemu-devel@nongnu.org; Mon, 08 Oct 2012 11:28:55 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TLFG5-00083O-DA for qemu-devel@nongnu.org; Mon, 08 Oct 2012 11:28:51 -0400 Received: from thoth.sbs.de ([192.35.17.2]:24228) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TLFG5-000833-3I for qemu-devel@nongnu.org; Mon, 08 Oct 2012 11:28:41 -0400 Message-ID: <5072F125.3010204@siemens.com> Date: Mon, 08 Oct 2012 17:28:37 +0200 From: Jan Kiszka MIME-Version: 1.0 References: <506F1934.5000002@siemens.com> <506F207A.70805@siemens.com> <5072782E.9090707@siemens.com> <5072EEB7.2070408@redhat.com> In-Reply-To: <5072EEB7.2070408@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] versatile: Push lsi initialization to the end List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: Peter Maydell , qemu-devel On 2012-10-08 17:18, Paolo Bonzini wrote: > 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 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); > + } It's not (only) about a missing event for the serial frontend, it's also about a spurious open event to the monitor. That generates unwanted output during startup. Jan -- Siemens AG, Corporate Technology, CT RTC ITP SDP-DE Corporate Competence Center Embedded Linux