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

[Ingo Molnar]

* Cyrill Gorcunov <gorcunov@xxxxxxxxx> 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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