On Tue, Apr 12, 2016 at 05:58:20PM +0300, Andy Shevchenko wrote: > On Tue, Apr 12, 2016 at 4:39 PM, Sudip Mukherjee > <sudipm.mukherjee@xxxxxxxxx> wrote: > > On Tuesday 12 April 2016 06:36 PM, Guenter Roeck wrote: > >> > >> On 04/11/2016 10:51 PM, Sudip Mukherjee wrote: > >>> > >>> The build of avr32 allmodconfig fails with the error: > >>> ERROR: "__avr32_udiv64" [drivers/watchdog/kempld_wdt.ko] undefined! > >>> > >> This means there is a direct 64 bit divide operation in the driver, > >> which we should identify and fix. > > This driver will quite likely never be used on AVR32. Do we need to > fix this due to some other architectures? > > > yes, there is. > > > > in function: kempld_wdt_set_stage_timeout() > > remainder = do_div(stage_timeout64, prescaler); > > > Any idea how to fix it? > > Not easy, however, prescaler value is ((1 << 21) - 1) which someone > might consider as (1 << 21) with lost in precision. > > Thus, shift on 20 bits right, add last bit to the value and shift on 1 > bit right more. > Sorry, I am missing something. do_div() should work fine with any 32 bit value as divisor, no matter what that value is. Why does it fail here ? And why does it work if I pass 0x1fffff as second parameter to do_div() directly ? Thanks, Guenter > -- > With Best Regards, > Andy Shevchenko > -- > To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe kernel-testers" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
