From: Robert Picco <Robert.Picco@hp.com>
To: Jesse Barnes <jbarnes@engr.sgi.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>,
Bjorn Helgaas <bjorn.helgaas@hp.com>,
Christoph Lameter <clameter@sgi.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
venkatesh.pallipadi@intel.com
Subject: Re: device driver for the SGI system clock, mmtimer
Date: Thu, 16 Sep 2004 14:17:42 -0400 [thread overview]
Message-ID: <4149D8C6.1060407@hp.com> (raw)
In-Reply-To: <200409161007.37015.jbarnes@engr.sgi.com>
Jesse Barnes wrote:
>On Thursday, September 16, 2004 8:52 am, Alan Cox wrote:
>
>
>>On Iau, 2004-09-16 at 17:09, Jesse Barnes wrote:
>>
>>
>>>I think Christoph already looked at that. And HPET doesn't provide mmap
>>>functionality, does it? I.e. allow a userspace program to dereference
>>>the counter register directly?
>>>
>>>
>>It can do but that assumes nothing else is mapped into the same page
>>that would be harmful or reveal information that should not be revealed
>>etc..
>>
>>
>
>And what about the register layout? mmtimer makes sure that the register is
>on a page by itself before it allows the mmap, and only exports the counter
>register itself. Can hpet do that?
>
>Jesse
>
>
>
The hpet driver checks that the mapping is page aligned. It's up to the
platform to provide this alignment. It's also dependent on the platform
for what resides in the page. Also the configured page size could
impact what is within the page.
next prev parent reply other threads:[~2004-09-16 18:10 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-16 16:03 device driver for the SGI system clock, mmtimer Bjorn Helgaas
2004-09-16 16:09 ` Jesse Barnes
2004-09-16 15:52 ` Alan Cox
2004-09-16 17:07 ` Jesse Barnes
2004-09-16 18:17 ` Robert Picco [this message]
2004-09-16 18:23 ` Jesse Barnes
2004-09-16 18:00 ` Robert Picco
2004-09-16 16:29 ` Marcello Barnaba
2004-09-16 16:30 ` Christoph Lameter
2004-09-16 18:14 ` Vojtech Pavlik
2004-09-16 18:35 ` Jesse Barnes
2004-09-16 20:34 ` Vojtech Pavlik
2004-09-16 18:46 ` Christoph Lameter
2004-09-20 21:53 ` Bjorn Helgaas
2004-09-16 16:32 ` Christoph Lameter
2004-09-16 16:54 ` Bjorn Helgaas
2004-09-16 18:07 ` Robert Picco
2004-09-16 20:05 ` Christoph Lameter
2004-09-17 1:34 ` Robert Picco
2004-09-16 18:17 ` Vojtech Pavlik
[not found] <Pine.LNX.4.58.0409082058140.28678@schroedinger.engr.sgi.com>
[not found] ` <20040908210537.585120c1.akpm@osdl.org>
2004-09-09 5:12 ` Christoph Lameter
2004-09-09 6:43 ` Jesse Barnes
2004-09-10 19:54 ` Christoph Lameter
2004-09-11 10:50 ` Christoph Hellwig
2004-09-11 15:32 ` Christoph Lameter
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