On Thu, Aug 1, 2019 at 2:26 PM Daniel Drake <dr...@endlessm.com> wrote: > > Hi, > > Working with a new consumer laptop based on AMD R7-3700U, we are > seeing a kernel panic during early boot (before the display > initializes). It's a new product and there is no previous known > working kernel version (tested 5.0, 5.2 and current linus master). > > We may have also seen this problem on a MiniPC based on AMD APU 7010 > from another vendor, but we don't have it in hands right now to > confirm that it's the exact same crash. > > earlycon shows the details: a NULL dereference under > setup_boot_APIC_clock(), which actually happens in > calibrate_APIC_clock(): > > /* Replace the global interrupt handler */ > real_handler = global_clock_event->event_handler; > global_clock_event->event_handler = lapic_cal_handler; > > global_clock_event is NULL here. This is a "reduced hardware" ACPI > platform so acpi_generic_reduced_hw_init() has set timer_init to NULL, > avoiding the usual codepaths that would set up global_clock_event. > IIRC, acpi_generic_reduced_hw_init() avoids initializing PIT, the status of this legacy device is unknown in ACPI hw-reduced mode.
> I tried the obvious: > if (!global_clock_event) > return -1; > No, the platform needs a global clock event, can you turn on some other clock source on your platform, like HPET? Thanks, -Aubrey > However I'm probably missing part of the big picture here, as this > only makes boot fail later on. It continues til the next point that > something leads to schedule(), such as a driver calling msleep() or > mark_readonly() calling rcu_barrier(), etc. Then it hangs. > > Is something missing in terms of timer setup here? Suggestions appreciated... > > Thanks > Daniel
