lkml.org 
[lkml]   [2019]   [Aug]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: setup_boot_APIC_clock() NULL dereference during early boot on reduced hardware platforms
On Thu, Aug 1, 2019 at 2:26 PM Daniel Drake <drake@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

\
 
 \ /
  Last update: 2019-08-01 09:17    [W:0.134 / U:0.080 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site