On Fri, Oct 04, 2013 at 11:29:58AM -0600, Bjorn Helgaas wrote: > [+cc Konrad, xen-devel] Hey Bjorn, Thanks! > > On Wed, Oct 02, 2013 at 04:43:46PM -0400, Aaron Opfer wrote: > > First time submitting the kernel dev list, so if I have demonstrated > > gross incompetence in some way, please cut me some slack. :) > > > > I discussed with Clemens Ladisch an issue I was having that I thought > > was related to the driver he authored for my soundcard, but on his > > suggestion I experimented with other PCI devices and we have narrowed > > the issue to the PCI Bridge. > > > > What hints me toward DMA handling being the fault is the following > > message I receive during kernel initialization after rebooting from an > > Xen hypervisor into a baremetal-kernel, without a power-cycle: > > > > [0.012815] dmar: DRHD: handling fault status reg 3 > > [0.012868] dmar: DMAR:[DMA Read] Request device [07:00.0] fault addr 7e00000 > > [0.012868] DMAR:[fault reason 02] Present bit in context entry is clear > > Presumably 07:00.0 is your soundcard, and apparently it did a DMA > read to 0x7e00000, which wasn't mapped by the IOMMU. > > > In addition to other hints, such as simple IO like changing the active > > port on the soundcard worked (I could hear the relays clicking) but > > not the functions that DMA would be used (streaming audio). > > > > The PCI devices in my system are connected via this device, as listed by lspci: > > > > 06:00.0 PCI bridge: ASMedia Technology Inc. ASM1083/1085 PCIe to PCI > > Bridge (rev 03) > > > > This PCI bridge works under bare-metal Linux normally (w/ various > > debian kernels stable/unstable/testing/backports), but under Xen > > Hypervisor the PCI devices connected exhibit bad behavior. > > So it fails with Xen but works otherwise? I assume there are other > PCI devices, too? Do they work? > > If you want to open a report at http://bugzilla.kernel.org, that would > be a handy place to attach a complete dmesg log and "lspci -vv" output > for more details. > > > For > > instance, aformentioned sound card outputs no sound and gets no > > microphone input at all, and an ethernet card causes a system lockup > > as soon as gnome's network manager attempts DHCP over it (presumably; > > I did not test this as thoroughly as the sound card). > > > > I've used Xen Hypervisors 4.1 and 4.2 and had the issues I described > > above with both of them. I was briefly running 4.3 but I did not test > > the device. So lets seperate some of these issues. The sound-card issue might be related to the Linux kernel Xen-SWIOTLB (fixed at some point)- so could you tell me what the kernel version you have? Xen 4.3 also has numerous fixes in the IOMMU path. > > > > Rev1 of the ASM1083 was apparently buggy to the point of being > > unusable, as Clemens pointed out. I would be disappointed if this > > device is similarly unsalvageable,but would be happier if this buggy > > hardware at the very least outputted warnings to users who attempt to > > use it (in Xen). > > > > All The Best, > > > > Aaron Opfer > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-pci" in > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
