Re: device driver for the SGI system clock, mmtimer

From: Jesse Barnes
Date: Thu Sep 16 2004 - 12:32:00 EST


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
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