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SubjectRe: [PATCH -tip] x86: apic LVTT - use APIC_DIVISOR on 64bit mode

* Cyrill Gorcunov <gorcunov@gmail.com> wrote:

> We use APIC_TDR_DIV_16 while setting APIC_TDCR (divisor) it happened
> this moment is hidden from __setup_APIC_LVTT caller. So we better
> increment caller 'clocks' value to not change current behaviour and
> use APIC_DIVISOR (as already done in 32bit version).
>
> The main benefit - unified procedure code for 32/64bit modes.

> Please review carefully. Any comments are welcome.
> I'm _not_ 100% sure if this patch is safe.

hm, how about the other caller to __setup_APIC_LVTT(),
lapic_timer_setup():

case CLOCK_EVT_MODE_ONESHOT:
__setup_APIC_LVTT(calibration_result,
mode != CLOCK_EVT_MODE_PERIODIC, 1);
break;

that will affect high-res timers. Wont calibration_result have the same
value after your patch as well, but only a 16th of it will be used in
__setup_APIC_LVTT(), causing 16 times shorter timeouts than intended?

I.e. are we fixing a bug, are we changing nothing, or are we introducing
a bug? :-)

Ingo


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