问题描述

直播NF5466M5服务器，产线预装作业程序RHEL6.7，工具包施用全包安装选用的习惯，直播进行察觉到USB产品不可施用，还有连结USB产品后数据丢失的状况。整理日记察觉到有以下的报错。Sep 22 11:02:48 localhost pulseaudio[7275]: pid.c: Stale PID file, overwriting.Sep 22 11:05:39 localhost kernel: usb 1-2: new low speed USB device number 4 using xhci_hcdSep 22 11:05:39 localhost kernel: usb 1-2: device descriptor read/64, error -71Sep 22 11:05:39 localhost kernel: xhci_hcd 0000:00:14.0: Setup ERROR: setup context command for slot 3.Sep 22 11:05:39 localhost kernel: hub 1-0:1.0: unable to enumerate USB device on port 2Sep 22 11:05:41 localhost kernel: dmar: DRHD: handling fault status reg 2Sep 22 11:05:41 localhost kernel: dmar: DMAR:[DMA Read] Request device [00:14.0] fault addr 0Sep 22 11:05:41 localhost kernel: DMAR:[fault reason 06] PTE Read access is not set

Sep 22 11:05:47 localhost kernel: xhci_hcd 0000:00:14.0: Timeout while waiting for a slot

Sep 22 11:05:56 localhost kernel: xhci_hcd 0000:00:14.0: Stopped the command ring failed, maybe the host is dead

Sep 22 11:05:56 localhost kernel: xhci_hcd 0000:00:14.0: Abort command ring failedSep 22 11:05:56 localhost kernel: xhci_hcd 0000:00:14.0: HC died; cleaning upSep 22 11:05:56 localhost kernel: hub 1-0:1.0: cannot reset port 2 (err = -19)Sep 22 11:05:56 localhost kernel: hub 1-0:1.0: cannot disable port 2 (err = -19)

涉及范围

M5/M4智能机型+匹配rhel6.x+全包装设操作使用软件。grub.conf及menu.lst有iommu=on的字体。

处理方案

关机重启后在菜單选定 的之时按e改进性能，将intel_iommu=on amd_iommu=on中的on改为off，进体统在这之后再改进grub.conf文档文件，改进文章与以前完全一致。

故障根因

sosreport中看到/proc/cmdline中有intel_iommu=on amd_iommu=on参数。

根据以往的经验，在一些机器上使用intel_iommu时偶尔会在插拔USB设备时出现系统hang住的问题；

在低版本内核中，还存在启动intel_iommu后kdump服务无法收集vmcore的问题，这些问题都和RHEL6版本的内核中相关的实现有关。