Messages in this thread | | | Date | Mon, 5 Jul 2021 08:21:07 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [kbuild-all] Re: kernel/time/clocksource-wdtest.c:47:22: warning: signed shift result (0x27BC86B00) requires 35 bits to represent, but 'long' only has 32 bits |
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On Mon, Jul 05, 2021 at 03:47:09PM +0800, Rong Chen wrote: > > > On 7/5/21 1:43 AM, Paul E. McKenney wrote: > > On Sun, Jul 04, 2021 at 05:42:36AM +0800, kernel test robot wrote: > > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master > > > head: 303392fd5c160822bf778270b28ec5ea50cab2b4 > > > commit: 1253b9b87e42ab6a3d5c2cb27af2bdd67d7e50ff clocksource: Provide kernel module to test clocksource watchdog > > > date: 11 days ago > > > config: mips-randconfig-r015-20210702 (attached as .config) > > > compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 9eb613b2de3163686b1a4bd1160f15ac56a4b083) > > > reproduce (this is a W=1 build): > > > wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross > > > chmod +x ~/bin/make.cross > > > # install mips cross compiling tool for clang build > > > # apt-get install binutils-mips-linux-gnu > > > # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1253b9b87e42ab6a3d5c2cb27af2bdd67d7e50ff > > > git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git > > > git fetch --no-tags linus master > > > git checkout 1253b9b87e42ab6a3d5c2cb27af2bdd67d7e50ff > > > # save the attached .config to linux build tree > > > COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=mips > > > > > > If you fix the issue, kindly add following tag as appropriate > > > Reported-by: kernel test robot <lkp@intel.com> > > > > > > All warnings (new ones prefixed by >>): > > > > > > > > kernel/time/clocksource-wdtest.c:47:22: warning: signed shift result (0x27BC86B00) requires 35 bits to represent, but 'long' only has 32 bits [-Wshift-overflow] > > > .mult = TICK_NSEC << JIFFIES_SHIFT, /* details above */ > > > ~~~~~~~~~ ^ ~~~~~~~~~~~~~ > > > 1 warning generated. > > You have CONFIG_HZ_24=y and this test module assumes HZ > 100, as noted > > just above the excerpt below: > > > > /* Assume HZ > 100. */ > > #define JIFFIES_SHIFT 8 > > > > So this is expected behavior. > > > > Would it help if I gave that comment some teeth, for example, as > > shown at the end of this email? > > Hi Paul, > > I have confirmed that the below change can avoid the warning.
Very good, and thank you! May I add your Tested-by?
Thanx, Paul
> Best Regards, > Rong Chen > > > > > ------------------------------------------------------------------------ > > > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > > index e1856030fa66..8f0ad6e4183c 100644 > > --- a/lib/Kconfig.debug > > +++ b/lib/Kconfig.debug > > @@ -2573,6 +2573,7 @@ config TEST_FPU > > config TEST_CLOCKSOURCE_WATCHDOG > > tristate "Test clocksource watchdog in kernel space" > > depends on CLOCKSOURCE_WATCHDOG > > + depends on HZ >= 100 > > help > > Enable this option to create a kernel module that will trigger > > a test of the clocksource watchdog. This module may be loaded > > _______________________________________________ > > kbuild-all mailing list -- kbuild-all@lists.01.org > > To unsubscribe send an email to kbuild-all-leave@lists.01.org >
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