Hi, is there any chance to get an old rt kernel running, by downgrading something or changing some settings, if this error happens [1]? It doesn't happen with a newer kernel [2], but newer kernels are not necessarily running good on my machine. I also wonder, when the location /sys/bus/pci/drivers/ohci_hcd/unbind changed to /sys/bus/pci/drivers/ohci-pci/unbind [3]. Regards, Ralf [1] [root@archlinux rocketmouse]# uname -rm 3.10.61-rt65-1-rt-lts x86_64 [root@archlinux rocketmouse]# rtirq status PID CLS RTPRIO NI PRI %CPU STAT COMMAND [snip] 202 FF 50 - 90 0.0 S irq/18-snd_hdsp [snip] [root@archlinux rocketmouse]# rtirq stop [root@archlinux rocketmouse]# rtirq start chrt: failed to set pid 202's policy: Function not implemented Setting IRQ priorities: start [snd_hdsp] irq=18 pid=202 prio=90: FAILED. [2] [root@archlinux rocketmouse]# uname -rm 4.5.4-1-ARCH x86_64 [root@archlinux rocketmouse]# rtirq status PID CLS RTPRIO NI PRI %CPU STAT COMMAND 323 FF 90 - 130 0.0 S irq/18-snd_hdsp [snip] [root@archlinux rocketmouse]# rtirq stop [root@archlinux rocketmouse]# rtirq start Setting IRQ priorities: start [snd_hdsp] irq=18 pid=323 prio=90: OK. [3] [root@archlinux rocketmouse]# echo -n "0000:00:13.2" > /sys/bus/pci/drivers/ohci_hcd/unbind bash: /sys/bus/pci/drivers/ohci_hcd/unbind: No such file or directory [root@archlinux rocketmouse]# echo -n "0000:00:13.4" > /sys/bus/pci/drivers/ohci_hcd/unbind bash: /sys/bus/pci/drivers/ohci_hcd/unbind: No such file or directory [root@archlinux rocketmouse]# rtirq status PID CLS RTPRIO NI PRI %CPU STAT COMMAND 323 FF 90 - 130 0.0 S irq/18-snd_hdsp [snip] 144 FF 50 - 90 0.1 S irq/17-ohci_hcd 146 FF 50 - 90 0.0 S irq/18-ohci_hcd 147 FF 50 - 90 0.0 S irq/17-ohci_hcd 148 FF 50 - 90 0.0 S irq/18-ohci_hcd [snip] [root@archlinux rocketmouse]# echo -n "0000:00:13.4" > /sys/bus/pci/drivers/ohci-pci/unbind [root@archlinux rocketmouse]# echo -n "0000:00:13.2" > /sys/bus/pci/drivers/ohci-pci/unbind [root@archlinux rocketmouse]# rtirq status PID CLS RTPRIO NI PRI %CPU STAT COMMAND 323 FF 90 - 130 0.0 S irq/18-snd_hdsp [snip] 144 FF 50 - 90 0.1 S irq/17-ohci_hcd 147 FF 50 - 90 0.0 S irq/17-ohci_hcd [snip]