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From: johan.adolfsson@axis.com
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To: "Oliver Xymoron" <oxymoron@waste.org>, <johan.adolfsson@axis.com>
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References: <01a301c2482c$51a00e40$b9b270d5@homeip.net> <20020820140346.GC19225@waste.org> <03f401c24867$2d5260c0$b9b270d5@homeip.net> <20020820170601.GD19225@waste.org>
Subject: Re: [RFC] Improved add_timer_randomness for __CRIS__ (instead of rdtsc())
Date: Tue, 20 Aug 2002 19:34:02 +0200
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> > Put an inline function or macro in asm/timex.h (?) together with an
> > ARCH_HAS_RANDOM_TIMESTAMP define?
> 
> I don't think we want to make it specific to random. I think we just
> want to call it hires. 
> 
> > E.g. like this for i386:
> > #define ARCH_HAS_RANDOM_TIMESTAMP
> > #define RANDOM_TIMESTAMP(time, num) do{\
..  
> > And then in random.c:
> > ifdef ARCH_HAS_RANDOM_TIMESTAMP
> >   RANDOM_TIMESTAMP(time, num);
> > #else
> >   time = jiffies;
> > #endif
> 
> Again, too random-specific. And we need a way to get the timescale.
> Perhaps something like:
> 
> speed=get_timestamp_khz;
> lowbits=get_hires_timestamp();

But isn't the "num ^= high;" a way to improve the randomness
and the high value doesn't really need to be linear to the time?
Thus it would be random-specific and not just a timestamp.

/Johan


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