Re: [PATCH v2 9/9] qemu-kvm: hpet: Add MSI support for in-kernel irqchip mode

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2011-04-26 15:30, Michael Tokarev wrote:
> 26.04.2011 17:19, Jan Kiszka wrote:
> 
>>  hw/hpet.c |   71 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
> 
>> +static int modifying_bit(uint64_t old, uint64_t new, uint64_t mask)
>> +{
>> +    return (old ^ new) & mask;
>> +}
> 
> Such constructs always look suspicious.  I'm not even sure anymore
> (after using C for over 20 years ;) that this works... how about
> 
>  return (old ^ new) & mask  ? 1 : 0;
> 
> instead, or something along this?  I mean, if sizeof(int)==4, how
> `return 1ULL<<32' will be interpreted in this context?  Tiny test
> program tells me it will return 0...

Good catch, will fix (doesn't bite use here, flags fit into 32 bit, but
nevertheless).

Jan

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