From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60017) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eC1Di-0001VN-E4 for qemu-devel@nongnu.org; Tue, 07 Nov 2017 05:35:08 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eC1Dc-0000HR-Im for qemu-devel@nongnu.org; Tue, 07 Nov 2017 05:35:02 -0500 Date: Tue, 7 Nov 2017 11:34:46 +0100 From: Cornelia Huck Message-ID: <20171107113446.6ac51e16.cohuck@redhat.com> In-Reply-To: References: <1e04415c-83d5-a6ac-f83f-d7a57b9b9868@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] Crash with pcie-pci-bridge on qemu-system-s390x List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Aleksandr Bezzubikov Cc: Marcel Apfelbaum , qemu-s390x@nongnu.org, Thomas Huth , QEMU Developers On Thu, 2 Nov 2017 17:59:58 +0300 Aleksandr Bezzubikov wrote: > 2017-11-02 17:42 GMT+03:00 Marcel Apfelbaum : > > On 02/11/2017 16:19, Thomas Huth wrote: > >> > >> Hi, > >> > > > > Hi Thomas, > > > > Hi Thomas, Marcel, > > >> seems like there's a new way to crash QEMU with the pcie-pci-bridge > >> device (using QEMU master branch of today): > >> > $ s390x-softmmu/qemu-system-s390x -nographic -S > >> QEMU 2.10.50 monitor - type 'help' for more information > >> (qemu) device_add pcie-pci-bridge,id=x > >> Segmentation fault (core dumped) > >> > > > > Thanks for noticing it. > > > >> Does anybody have a clue what might be wrong here? > >> > > > > It was tested with X86 and I think aarch64. > > I am not sure how it would work with or if we > > really need it for s390. > > > > We need the device to start a PCI hierarchy by plugging > > it to PCIe Root Port. If I understand correctly s390 > > does not use PCIe Root Ports and may not need it. > > > > Personally I can see 2 issues here: > 1) [Marcel's already mentioned it] It seems that s390x machines have > only pure PCI hosts, > that's why it's a bit weird to put pcie-pci-bridge into the host > 2) The actual segfault cause is bridge parent bus not having a parent > device (somehow). > Maybe it's a consequence of point 1) Yes. PCI on s390x is weird; we basically have no topology and just make one up (of which the guest sees nothing at all). > > > If the assumption is correct I suppose we should only > > be compiled into the above archs. > > If you agree, I can post a patch for this. I think disabling this for s390x makes sense.