On 07.07.2023 10:04, Simone Ballarin wrote: > Il giorno ven 7 lug 2023 alle ore 09:04 Jan Beulich <jbeul...@suse.com> ha > scritto: > >> On 07.07.2023 08:50, Simone Ballarin wrote: >>> Il giorno gio 6 lug 2023 alle ore 18:22 Jan Beulich <jbeul...@suse.com> >> ha >>> scritto: >>> >>>> On 06.07.2023 18:08, Simone Ballarin wrote: >>>>> Il giorno gio 6 lug 2023 alle ore 10:26 Jan Beulich <jbeul...@suse.com >>> >>>> ha >>>>> scritto: >>>>> >>>>>> On 05.07.2023 17:26, Simone Ballarin wrote: >>>>>>> --- a/xen/arch/x86/apic.c >>>>>>> +++ b/xen/arch/x86/apic.c >>>>>>> @@ -1211,7 +1211,7 @@ static void __init calibrate_APIC_clock(void) >>>>>>> * Setup the APIC counter to maximum. There is no way the lapic >>>>>>> * can underflow in the 100ms detection time frame. >>>>>>> */ >>>>>>> - __setup_APIC_LVTT(0xffffffff); >>>>>>> + __setup_APIC_LVTT(0xffffffffU); >>>>>> >>>>>> While making the change less mechanical, we want to consider to switch >>>>>> to ~0 in this and similar cases. >>>>>> >>>>> >>>>> Changing ~0U is more than not mechanical: it is possibly dangerous. >>>>> The resulting value could be different depending on the architecture, >>>>> I prefer to not make such kind of changes in a MISRA-related patch. >>>> >>>> What do you mean by "depending on the architecture", when this is >>>> x86-only code _and_ you can check what type parameter the called >>>> function has? >>> >>> Ok, I will change these literals in ~0U in the next submission. >> >> Except that I specifically meant ~0, not ~0U. We mean "maximum value" >> here, and at the call site it doesn't matter how wide the function >> parameter's type is. If it was 64-bit, ~0U would not do what is wanted. > > ~0 is not a MISRA-compliant solution since bitwise operations on signed > integers have implementation-defined behavior. This solution definitively > violates Rule 10.1.
So if we adopted that rule (we didn't so far), we'd have to e.g. change all literal number shift counts to have U suffixes, no matter that without the suffix it is still entirely obvious that the numbers are unsigned? I'm afraid that'll face my opposition ... Jan
