On 07/31/2013 12:34 AM, Sören Brinkmann wrote: > On Tue, Jul 30, 2013 at 10:47:15AM +0200, Daniel Lezcano wrote: >> On 07/30/2013 02:03 AM, Sören Brinkmann wrote: >>> Hi Daniel, >>> >>> On Mon, Jul 29, 2013 at 02:51:49PM +0200, Daniel Lezcano wrote: >>> (snip) >>>> >>>> the CPUIDLE_FLAG_TIMER_STOP flag tells the cpuidle framework the local >>>> timer will be stopped when entering to the idle state. In this case, the >>>> cpuidle framework will call clockevents_notify(ENTER) and switches to a >>>> broadcast timer and will call clockevents_notify(EXIT) when exiting the >>>> idle state, switching the local timer back in use. >>> >>> I've been thinking about this, trying to understand how this makes my >>> boot attempts on Zynq hang. IIUC, the wrongly provided TIMER_STOP flag >>> would make the timer core switch to a broadcast device even though it >>> wouldn't be necessary. But shouldn't it still work? It sounds like we do >>> something useless, but nothing wrong in a sense that it should result in >>> breakage. I guess I'm missing something obvious. This timer system will >>> always remain a mystery to me. >>> >>> Actually this more or less leads to the question: What is this >>> 'broadcast timer'. I guess that is some clockevent device which is >>> common to all cores? (that would be the cadence_ttc for Zynq). Is the >>> hang pointing to some issue with that driver? >> >> If you look at the /proc/timer_list, which timer is used for broadcasting ? > > So, the correct run results (full output attached). > > The vanilla kernel uses the twd timers as local timers and the TTC as > broadcast device: > Tick Device: mode: 1 > > Broadcast device > Clock Event Device: ttc_clockevent > > When I remove the offending CPUIDLE flag and add the DT fragment to > enable the global timer, the twd timers are still used as local timers > and the broadcast device is the global timer: > Tick Device: mode: 1 > > Broadcast device > > Clock Event Device: arm_global_timer > > Again, since boot hangs in the actually broken case, I don't see way to > obtain this information for that case.
Can't you use the maxcpus=1 option to ensure the system to boot up ? -- <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | <http://twitter.com/#!/linaroorg> Twitter | <http://www.linaro.org/linaro-blog/> Blog -- 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/
