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 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. 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. 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
