From mboxrd@z Thu Jan  1 00:00:00 1970
From: Michael Tokarev <mjt@tls.msk.ru>
Subject: Re: [PATCH v2 9/9] qemu-kvm: hpet: Add MSI support for in-kernel
 irqchip mode
Date: Tue, 26 Apr 2011 17:30:55 +0400
Message-ID: <4DB6C90F.4090401@msgid.tls.msk.ru>
References: <cover.1303823975.git.jan.kiszka@siemens.com> <3d089633897515a214af032ed633342a7001945f.1303823975.git.jan.kiszka@siemens.com>
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Cc: Avi Kivity <avi@redhat.com>, Marcelo Tosatti <mtosatti@redhat.com>,
	kvm@vger.kernel.org, "Michael S. Tsirkin" <mst@redhat.com>
To: Jan Kiszka <jan.kiszka@siemens.com>
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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...

/mjt