On Sat, Apr 30, 2016 at 07:38:28PM +0100, Sudip Mukherjee wrote: > On Tue, Apr 12, 2016 at 11:01:28AM -0700, Guenter Roeck wrote: > > 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 ? > > Please let me know what i can do here to help solve the problem. > linux-next continues to fail for avr32, and to make matters worse we > also have the similar problem in btrfs. > > ERROR: "__avr32_udiv64" [fs/btrfs/btrfs.ko] undefined! > ERROR: "__avr32_udiv64" [drivers/watchdog/kempld_wdt.ko] undefined! > > Adding Chris to CC if he has some idea how to solve this error for btrfs. > Build log for next-20160429 is at: > https://travis-ci.org/sudipm-mukherjee/parport/jobs/126581065 > Try the patch below. Guenter --- >From d2f541c46ae2bf599d9aa3be0682cfac76742ebf Mon Sep 17 00:00:00 2001 From: Guenter Roeck <linux@xxxxxxxxxxxx> Date: Sat, 30 Apr 2016 17:29:14 -0700 Subject: [PATCH] avr32: __div64_const32 is not ok Building avr32 images may fail with errors such as ERROR: "__avr32_udiv64" [fs/btrfs/btrfs.ko] undefined! ERROR: "__avr32_udiv64" [drivers/watchdog/kempld_wdt.ko] undefined! gcc for avr32 generates those symbols for certain constants used as divisor in do_div(). The problem can be avoided by setting __div64_const32_is_OK to false for the architecture. Cc: Sudip Mukherjee <sudipm.mukherjee@xxxxxxxxx> Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx> --- arch/avr32/include/asm/div64.h | 3 +++ 1 file changed, 3 insertions(+) create mode 100644 arch/avr32/include/asm/div64.h diff --git a/arch/avr32/include/asm/div64.h b/arch/avr32/include/asm/div64.h new file mode 100644 index 000000000000..1f3328e178df --- /dev/null +++ b/arch/avr32/include/asm/div64.h @@ -0,0 +1,3 @@ +#define __div64_const32_is_OK false + +#include <asm-generic/div64.h> -- 2.5.0 -- 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
