linux-kernel - Re: [PATCH] RTC: Add mmap method to rtc character driver

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Message-Id: <1153854412.8932.46.camel@laptopd505.fenrus.org>
Date:	Tue, 25 Jul 2006 21:06:52 +0200
From:	Arjan van de Ven <arjan@...radead.org>
To:	Neil Horman <nhorman@...driver.com>
Cc:	linux-kernel@...r.kernel.org, a.zummo@...ertech.it,
	jg@...edesktop.org
Subject: Re: [PATCH] RTC: Add mmap method to rtc character driver


> > well the idea that has been tossed about a few times is using a vsyscall
> > function that either calls into the kernel, or directly uses the hpet
> > page (which can be user mapped) to get time information that way... 
> > or even would use rdtsc in a way the kernel knows is safe (eg corrected
> > for the local cpu's speed and offset etc etc).
> > 
> Ok, that makes sense, although thats only going to be supportable on hpet
> enabled systems right?  

well it's only going to be *fast* on hpet enabled systems (which should
be the *vast* majority nowadays if it wasn't for some silly bios
defaults by some vendors); all others can just fall back to other
methods. The beauty of the vsyscall concept :)


-- 
if you want to mail me at work (you don't), use arjan (at) linux.intel.com

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