On 14-04-01 05:59 PM, Brown, Len wrote: >> I've got an eval board with a 1.7GHz Avaton/C2000 that hangs at boot >> shortly after the idle driver registration -- typically 1/2 dozen >> dmesg lines later, around rtc init, or net stack init. > > Paul, > Please boot the failing board with "intel_idle.max_cstate=0" > to disable intel_idle entirely, and then show the C-states > exported by acpi_idle, that predumably, are stable on both boards: > > dmesg | grep idle > grep . /sys/devices/system/cpu/cpu0/cpuidle/*/* > > Then go back and boot with "intel_idle.max_cstate=N" > where N is incremented by 1 until when the system fails > and note the largest N that still works.
The dying board works for N=1, fails for N=2. root@localhost:/sys/devices/system/cpu/cpuidle# grep . * current_driver:intel_idle current_governor_ro:menu root@localhost:/sys/devices/system/cpu/cpuidle# dmesg|grep idle [ 0.000000] Command line: BOOT_IMAGE=/boot/bzImage-current console=tty0 noinitrd root=/dev/sda4 rw ip=dhcp selinux=0 enforcing=0 intel_idle.max_cstate=1 [ 0.000000] Kernel command line: BOOT_IMAGE=/boot/bzImage-current console=tty0 noinitrd root=/dev/sda4 rw ip=dhcp selinux=0 enforcing=0 intel_idle.max_cstate=1 [ 0.000000] RCU dyntick-idle grace-period acceleration is enabled. [ 0.217203] cpuidle: using governor ladder [ 0.217309] cpuidle: using governor menu [ 0.840598] intel_idle: MWAIT substates: 0x33000020 [ 0.840662] intel_idle: v0.4 model 0x4D [ 0.840668] intel_idle: lapic_timer_reliable_states 0x2 [ 0.840673] intel_idle: max_cstate 1 reached root@localhost:/sys/devices/system/cpu/cpuidle# Another interesting data point -- the dying board doesn't die if I boot 3.14's x86-64 defconfig. Nothing immediately jumps out at me in the dying .config ; there are a few tweaks in there like RCU_NOCB etc. that I'll have to weed out with a pseudo .config bisect I guess.... I'll go get the N=1 and N=2 data for the working board next. Paul. -- > >> The interesting part is that a nearly identical board, but with >> different (newer/faster) CPU and newer BIOS doesn't have the hang. > > Possibly an electrical bug in the earlier board. > Maybe they worked around it by disabling a C-state in ACPI > and didn't test upstream Linux? > > I'd be interested in the acpi_idle output above for both the > new and old boards to see if they are exporting different states > on the two boards. > > dmidecode isn't useful in this case. The CPUID in /proc/cpuinfo > may be useful if the problem turns out to be associated with > some stepping. > > thanks, > -Len > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
