Dear Daniel, On Tue, 15 Dec 2015 21:59:30 +0100 Daniel Lezcano wrote:
> On 11/25/2015 04:42 PM, Jisheng Zhang wrote: > > Let's assume the counter value is 0xf000000, the pistachio clocksource > > read cycles function would return 0xffffffff0fffffff, but it should > > return 0xfffffff. > > > > We fix this issue by calculating bitwise-not counter, then cast to > > cycle_t. > > > > Signed-off-by: Jisheng Zhang <[email protected]> > > Hi Jisheng, > > I tried to reproduce this behavior on x86_64 but without success. > > On which architecture did you produce this result ? Do you have a simple > test program to check with ? I have no HW platforms with pistachio, just read the code and run the following test code in x86_64 and x86_32: #include <stdio.h> unsigned long long pistachio_clocksource_read_cycles() { unsigned int counter = 0xf000000; return ~(unsigned long long)counter; } int main() { printf("%llx\n", pistachio_clocksource_read_cycles()); return 0; } Thanks, Jisheng -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
