Il giorno gio, 27/08/2020 alle 00.28 +0200, Giuseppe Sacco ha scritto: > Hello Christophe, > > Il giorno mer, 26/08/2020 alle 15.53 +0200, Christophe Leroy ha > scritto: > [...] > > If there is no warning, then the issue is something else, bad luck. > > > > Could you increase the loglevel and try again both with and without > > VMAP_STACK ? Maybe we'll get more information on where it stops. > > The problem is related to the CPU frequency changes. This is where the > system stop: cpufreq get the CPU frequency limits and then start the > default governor (performance) and then calls function > cpufreq_gov_performance_limits() that never returns. > > Rebuilding after enabling pr_debug for cpufreq.c, I've got some more > lines of output: > > cpufreq: setting new policy for CPU 0: 667000 - 867000 kHz > cpufreq: new min and max freqs are 667000 - 867000 kHz > cpufreq: governor switch > cpufreq: cpufreq_init_governor: for CPU 0 > cpufreq: cpufreq_start_governor: for CPU 0 > cpufreq: target for CPU 0: 867000 kHz, relation 1, requested 867000 kHz > cpufreq: __target_index: cpu: 0, oldfreq: 667000, new freq: 867000 > cpufreq: notification 0 of frequency transition to 867000 kHz > cpufreq: saving 133328 as reference value for loops_per_jiffy; freq is 667000 > kHz > > no more lines are printed. I think this output only refers to the > notification sent prior to the frequency change. > > I was thinking that selecting a governor that would run at 667mHz would > probably skip the problem. I added cpufreq.default_governor=powersave > to the command line parameters but it did not work: the selected > governor was still performance and the system crashed.
I kept following the thread and found that CPU frequency is changed in function pmu_set_cpu_speed() in file drivers/cpufreq/pmac32-cpufreq.c. As first thing, the function calls the macro preempt_disable() and this is where it stops. Bye, Giuseppe
