From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from list by lists.gnu.org with archive (Exim 4.71) id 1dpsL0-0005Vk-DK for mharc-qemu-trivial@gnu.org; Thu, 07 Sep 2017 04:39:02 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39746) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dpsKu-0005RL-Kj for qemu-trivial@nongnu.org; Thu, 07 Sep 2017 04:39:01 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dpsKp-0006Im-Sv for qemu-trivial@nongnu.org; Thu, 07 Sep 2017 04:38:56 -0400 Received: from mx1.redhat.com ([209.132.183.28]:32892) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dpsKd-0006Ch-CN; Thu, 07 Sep 2017 04:38:39 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 44FA1C0587E5; Thu, 7 Sep 2017 08:38:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 44FA1C0587E5 Authentication-Results: ext-mx08.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx08.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=otubo@redhat.com Received: from vader (ovpn-117-116.ams2.redhat.com [10.36.117.116]) by smtp.corp.redhat.com (Postfix) with SMTP id 60D8360603; Thu, 7 Sep 2017 08:38:30 +0000 (UTC) Date: Thu, 7 Sep 2017 10:38:29 +0200 From: Eduardo Otubo To: Eduardo Habkost Cc: Markus Armbruster , mst@redhat.com, qemu-trivial@nongnu.org, qemu-devel@nongnu.org, Alexander Graf , qemu-ppc@nongnu.org, pbonzini@redhat.com, David Gibson Message-ID: <20170907083829.GB2441@vader> References: <20170901110332.32650-1-otubo@redhat.com> <20170901143016.GK7570@localhost.localdomain> <87lglyzb3p.fsf@dusky.pond.sub.org> <20170901154430.GN7570@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20170901154430.GN7570@localhost.localdomain> User-Agent: Mutt/1.8.3+47 (5f034395e53d) (2017-05-23) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Thu, 07 Sep 2017 08:38:38 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-trivial] [Qemu-devel] [PATCH] dma/i82374: avoid double creation of i82374 device X-BeenThere: qemu-trivial@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 07 Sep 2017 08:39:01 -0000 On Fri, Sep 01, 2017 at 12:44:30PM -0300, Eduardo Habkost wrote: > On Fri, Sep 01, 2017 at 05:34:34PM +0200, Markus Armbruster wrote: > > Eduardo Habkost writes: > > > > > i82374 is compiled in only on ppc and sh4, so I'm CCing the > > > maintainers for those architectures. > > > > > > On Fri, Sep 01, 2017 at 01:03:32PM +0200, Eduardo Otubo wrote: > > >> When used with the following command line: > > >> > > >> ./ppc64-softmmu/qemu-system-ppc64 -S -machine 40p,accel=tcg -device i82374 > > >> > > >> QEMU with machine type 40p already creates the device i82374. If > > >> specified in the command line, it will try to create it again, hence > > >> generating the error. Well pointed, forgot to describe the actual error. I may inlcude for the next version of the patch. For for correctness sake, here it is: ./ppc64-softmmu/qemu-system-ppc64 -S -machine 40p,accel=tcg -device i82374 qemu-system-ppc64: hw/isa/isa-bus.c:110: isa_bus_dma: Assertion `!bus->dma[0] && !bus->dma[1]' failed. Aborted (core dumped) > > > > > > Which error? > > > > > > > > >> One way to avoid this problem is to set > > >> user_creatable=false. > > >> > > >> Signed-off-by: Eduardo Otubo > > > > > > The patch does more than just avoiding double creation: it > > > prevents usage of "-device i82374" completely. > > > > > > Maybe nobody needs it to work with -device today (would the > > > device even work?) and it is OK to set user_creatable=false until > > > we fix the crash. But we need to be sure of that. > > > > > >> --- > > >> hw/dma/i82374.c | 1 + > > >> 1 file changed, 1 insertion(+) > > >> > > >> diff --git a/hw/dma/i82374.c b/hw/dma/i82374.c > > >> index 6c0f975df0..5275d822e0 100644 > > >> --- a/hw/dma/i82374.c > > >> +++ b/hw/dma/i82374.c > > >> @@ -139,6 +139,7 @@ static void i82374_class_init(ObjectClass *klass, void *data) > > >> dc->realize = i82374_realize; > > >> dc->vmsd = &vmstate_i82374; > > >> dc->props = i82374_properties; > > >> + dc->user_creatable = false; > > > > > > A "Reason:" comment explaining why user_creatable=false is > > > mandatory. See the comment above user_creatable declaration in > > > qdev-core.h for reference. > > > > > > I suggest the following: > > > > > > /* > > > * Reason: i82374_realize() crashes (assertion failure inside isa_bus_dma() > > > * if the device is instantiated twice. > > > */ I agree with the comment above. If there's nothing left to fix/add I'll just send a v2 for this shortly. > > > > We need to find out *why* it crashes. Once we know, we can likely write > > a better comment. > > It crashes because isa_bus_dma() isn't supposed to be called > twice for the same bus. > > Making isa_bus_dma()/DMA_init()/i82374_realize() return an error > instead of asserting would be even better than setting > user_creatable=false. > > -- > Eduardo > -- Eduardo Otubo Senior Software Engineer @ RedHat