Hello, My PCIe host bridge is supposed to support AER, so I enabled kernel support, out of curiosity. For these tests, I plugged a USB3 card into the PCIe slot. I see two classes of reports. 1) When the system is idling, with no USB device plugged into the PCIe card, I occasionally see these: [ 5003.638675] pcieport 0000:00:00.0: AER: Multiple Corrected error received: id=0000 [ 5003.646365] pcieport 0000:00:00.0: PCIe Bus Error: severity=Corrected, type=Physical Layer, id=0000(Receiver ID) [ 5003.656991] pcieport 0000:00:00.0: device [1105:0028] error status/mask=00000001/00002000 [ 5003.665566] pcieport 0000:00:00.0: [ 0] Receiver Error (First) [ 6104.766906] pcieport 0000:00:00.0: AER: Multiple Corrected error received: id=0000 [ 6104.774579] pcieport 0000:00:00.0: PCIe Bus Error: severity=Corrected, type=Physical Layer, id=0000(Receiver ID) [ 6104.785140] pcieport 0000:00:00.0: device [1105:0028] error status/mask=00000001/00002000 [ 6104.793701] pcieport 0000:00:00.0: [ 0] Receiver Error (First) [ 8388.051130] pcieport 0000:00:00.0: AER: Multiple Corrected error received: id=0000 [ 8388.058818] pcieport 0000:00:00.0: PCIe Bus Error: severity=Corrected, type=Physical Layer, id=0000(Receiver ID) [ 8388.069429] pcieport 0000:00:00.0: device [1105:0028] error status/mask=00000001/00002000 [ 8388.078041] pcieport 0000:00:00.0: [ 0] Receiver Error (First) [11022.907894] pcieport 0000:00:00.0: AER: Multiple Corrected error received: id=0000 [11022.915570] pcieport 0000:00:00.0: PCIe Bus Error: severity=Corrected, type=Physical Layer, id=0000(Receiver ID) [11022.926102] pcieport 0000:00:00.0: device [1105:0028] error status/mask=00000001/00002000 [11022.934666] pcieport 0000:00:00.0: [ 0] Receiver Error (First) 1105:0024 is the rev1 host bridge. 1105:0028 is the rev2 host bridge. I'll let a rev1 host bridge idle for a long time, but I don't remember seeing these reports on rev1. 2) When I unplug my USB3 Flash drive, I always get some kind of error from the USB framework, and sometimes they are coupled with AER messages. [ 40.158166] pcieport 0000:00:00.0: AER: Uncorrected (Non-Fatal) error received: id=0000 [ 40.166291] pcieport 0000:00:00.0: PCIe Bus Error: severity=Uncorrected (Non-Fatal), type=Transaction Layer, id=0000(Requester ID) [ 40.178519] pcieport 0000:00:00.0: device [1105:0024] error status/mask=00004000/00000000 [ 40.187033] pcieport 0000:00:00.0: [14] Completion Timeout (First) [ 40.193957] pcieport 0000:00:00.0: broadcast error_detected message [ 40.200345] pcieport 0000:00:00.0: AER: Device recovery failed [ 40.485352] xhci_hcd 0000:01:00.0: Cannot set link state. [ 40.490887] usb usb2-port2: cannot disable (err = -32) [ 40.496070] usb 2-2: USB disconnect, device number 2 [ 40.508478] pcieport 0000:00:00.0: AER: Uncorrected (Non-Fatal) error received: id=0000 [ 40.517291] pcieport 0000:00:00.0: PCIe Bus Error: severity=Uncorrected (Non-Fatal), type=Transaction Layer, id=0000(Requester ID) [ 40.529266] pcieport 0000:00:00.0: device [1105:0024] error status/mask=00004000/00000000 [ 40.538284] pcieport 0000:00:00.0: [14] Completion Timeout (First) [ 40.545233] pcieport 0000:00:00.0: broadcast error_detected message [ 40.551883] pcieport 0000:00:00.0: AER: Device recovery failed [ 40.557859] pcieport 0000:00:00.0: AER: Uncorrected (Non-Fatal) error received: id=0000 [ 40.566367] pcieport 0000:00:00.0: PCIe Bus Error: severity=Uncorrected (Non-Fatal), type=Transaction Layer, id=0000(Requester ID) [ 40.578667] pcieport 0000:00:00.0: device [1105:0024] error status/mask=00004000/00000000 [ 40.587098] pcieport 0000:00:00.0: [14] Completion Timeout (First) [ 40.593950] pcieport 0000:00:00.0: broadcast error_detected message [ 40.600268] pcieport 0000:00:00.0: AER: Device recovery failed [ 40.606148] pcieport 0000:00:00.0: AER: Uncorrected (Non-Fatal) error received: id=0000 [ 40.614223] pcieport 0000:00:00.0: PCIe Bus Error: severity=Uncorrected (Non-Fatal), type=Transaction Layer, id=0000(Requester ID) [ 40.626046] pcieport 0000:00:00.0: device [1105:0024] error status/mask=00004000/00000000 [ 40.634455] pcieport 0000:00:00.0: [14] Completion Timeout (First) [ 40.641295] pcieport 0000:00:00.0: broadcast error_detected message [ 40.647605] pcieport 0000:00:00.0: AER: Device recovery failed Should I worry over these reports? (The first set looks harmless, the second one looks bad.) # /usr/sbin/lspci -v 00:00.0 PCI bridge: Sigma Designs, Inc. Device 0024 (rev 01) (prog-if 00 [Normal decode]) Flags: bus master, fast devsel, latency 0, IRQ 26 Bus: primary=00, secondary=01, subordinate=01, sec-latency=0 I/O behind bridge: 00000000-00000fff [size=4K] Memory behind bridge: 04000000-040fffff [size=1M] Prefetchable memory behind bridge: 00000000-000fffff [size=1M] Capabilities: [50] MSI: Enable+ Count=1/4 Maskable- 64bit+ Capabilities: [78] Power Management version 3 Capabilities: [80] Express Root Port (Slot-), MSI 03 Capabilities: [100] Virtual Channel Capabilities: [800] Advanced Error Reporting Kernel driver in use: pcieport 01:00.0 USB controller: Renesas Technology Corp. uPD720201 USB 3.0 Host Controller (rev 03) (prog-if 30 [XHCI]) Flags: bus master, fast devsel, latency 0, IRQ 28 Memory at 54000000 (64-bit, non-prefetchable) [size=8K] Capabilities: [50] Power Management version 3 Capabilities: [70] MSI: Enable+ Count=1/8 Maskable- 64bit+ Capabilities: [90] MSI-X: Enable- Count=8 Masked- Capabilities: [a0] Express Endpoint, MSI 00 Capabilities: [100] Advanced Error Reporting Capabilities: [150] Latency Tolerance Reporting Kernel driver in use: xhci_hcd Regards.