From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58479) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XRza6-0002Vw-Kr for qemu-devel@nongnu.org; Thu, 11 Sep 2014 04:18:26 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XRzZz-0004AJ-57 for qemu-devel@nongnu.org; Thu, 11 Sep 2014 04:18:18 -0400 Received: from mail-pa0-f41.google.com ([209.85.220.41]:56748) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XRzZy-0004AD-W8 for qemu-devel@nongnu.org; Thu, 11 Sep 2014 04:18:11 -0400 Received: by mail-pa0-f41.google.com with SMTP id bj1so8098783pad.0 for ; Thu, 11 Sep 2014 01:18:10 -0700 (PDT) Message-ID: <54115AB9.8080700@ozlabs.ru> Date: Thu, 11 Sep 2014 18:18:01 +1000 From: Alexey Kardashevskiy MIME-Version: 1.0 References: <1410419467-9932-1-git-send-email-aik@ozlabs.ru> <1410420145.6138.7.camel@nilsson.home.kraxel.org> In-Reply-To: <1410420145.6138.7.camel@nilsson.home.kraxel.org> Content-Type: text/plain; charset=koi8-r Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] ohci: Stop OHCI bus when PCI bus master is disabled List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gerd Hoffmann Cc: qemu-ppc@nongnu.org, qemu-devel@nongnu.org, Alexander Graf On 09/11/2014 05:22 PM, Gerd Hoffmann wrote: > On Do, 2014-09-11 at 17:11 +1000, Alexey Kardashevskiy wrote: >> When the guest performs kexec() (for example, as a part of kdump), >> new kernel does PCI probing. As a part of it, PCI_COMMAND_MASTER >> gets disabled which disables bus master memory region. >> Since ohci_frame_boundary() timer is not stopped at this point >> as OHCI device was not reset, the device tries accessing DMA memory, >> fails and ends up in ohci_die() producing errors: >> >> usb-ohci: HCCA read error at 30000000 >> ohci_die: DMA error > > Which is the correct behavior. > > IMHO the kernel should stop ohci before doing kexec. To be precise, it is kdump. > Independant of that we can move the ohci error logging to tracepoints, > so ohci emulation is silent by default. That is the other way to go, yes. -- Alexey