I'm never sure whether it's best to continue things like this on the mailing list so everyone can follow along or in the Bugzilla entry...
On Sat, 5 Mar 2005, Andrew Morton wrote: > Begin forwarded message: > > Date: Sat, 5 Mar 2005 13:06:01 -0800 > From: [EMAIL PROTECTED] > To: [EMAIL PROTECTED] > Subject: [Bug 4294] kexec : on reboot, kernel hangs when reading > /proc/bus/usb/devices > > > http://bugme.osdl.org/show_bug.cgi?id=4294 > > > > > > ------- Additional Comments From [EMAIL PROTECTED] 2005-03-05 13:06 ------- > Created an attachment (id=4676) > --> (http://bugme.osdl.org/attachment.cgi?id=4676&action=view) > sysrq-t output > > > I hacked /etc/rc.rc/rc.sysinit to comment out the lines which read > /proc/usb/devices, so I could boot to initlevel 1. Here is the scenario : > > # #do not unload uhci-hcd > # kexec --load --initrd=/boot/initrd-2.6.11-mm1.img > '--command-line=root=/dev/hda6 init 1' /boot/vmlinuz-2.6.11-mm1 > # reboot > [ wait for the command prompt ] > # /etc/init.d/syslog start > # cat /proc/usb/devices & > [ press sysrq-t ] > > One can see 2 processus in 'D' state : > - khubd in wait_for_completion > - cat in __down/__down_failed/.text.lock.usb/usb_device_read > > also; note the message before an after Sysrq-t : > new low speed USB device using uhci_hcd and address 4 > device not accepting address 4, error -110 > > > FYI : > # cat /proc/interrupts > CPU0 > 0: 1535222 XT-PIC timer > 1: 6982 XT-PIC i8042 > 2: 0 XT-PIC cascade > 5: 1644 XT-PIC uhci_hcd:usb1, uhci_hcd:usb2, eth0, Ensoniq > AudioPCI > 7: 0 XT-PIC parport0 > 9: 0 XT-PIC acpi > 10: 2 XT-PIC ohci1394 > 12: 21150 XT-PIC i8042 > 14: 11182 XT-PIC ide0 > 15: 36076 XT-PIC ide1 > NMI: 0 > LOC: 0 > ERR: 0 > MIS: 0 What's happening is that the system is failing to initialize the mouse correctly. There are multiple retries (and multiple _layers_ of retries!) and the timeout is set to 5 seconds. Hence the delays apparent in your syslog. During that time the /proc/bus/usb/devices file is basically locked, so the process attempting to read it gets blocked. I assume nothing like this happens during a normal bootup, only when you use kexec? Actually I'm not at all familiar with how kexec works; can someone provide a quick explanation? If you rmmod uhci-hcd before the kexec and then modprobe it afterward, do detection and initialization of the mouse work okay? Assuming yes, it appears that uhci-hcd isn't reacting well to kexec. How does kexec impinge on the driver, and what is it supposed to do? Alan Stern P.S.: For a possibly related bug report, see http://bugme.osdl.org/show_bug.cgi?id=4276 ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click _______________________________________________ [email protected] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
