Subject: Re: [BUG] skge 0000:02:05: read data parity error

From: Greg KH <[email-masked]>
Date: Mon, 14 Jan 2008 13:30:54 -0800

On Mon, Jan 14, 2008 at 11:01:05PM +0200, Adrian Bunk wrote:
> On Mon, Jan 14, 2008 at 12:52:00PM -0800, Stephen Hemminger wrote:
> > On Mon, 14 Jan 2008 20:57:49 +0100
> > "Oliver Pinter (Pint??r Oliv??r)" <[email-masked]> wrote:
> > 
> > > Hi All!
> > > 
> > > It is fully reproductable under 2.6.22.15, 2.6.23.13 (all tainted and
> > > not tainted [4 different kernel] ) and 2 different PC:
> > > 
> > > [BUG] skge 0000:02:05: read data parity error
> > > [BUG] skge 0000:02:05: read data parity error
> > > 
> > > steps:
> > > 1. login as root
> > > 2. start mc
> > > 3. cd /sys/bus/pci/drivers/skge/0000:02:05.0
> > > 4. press F3 (mcview) on resource0
> > > 5. the system hang up, without panic or bug ... only this message
> > > printed 2x: [BUG] skge 0000:02:05: read data parity error
> > 
> > This is not a bug.
> > 
> > The hardware has some debug registers that if accessed cause a read
> > back to the host. Since this can point anywhere, it will cause errors
> > or system hang.
> > 
> > The point is don't do it.
> 
> Is it really a good idea that _reading_ files under /sys can kill your 
> machine?

No, but mmapping them as root and then doing bad things with that data
isn't recommended :)

Note that this is a special file, just like the ones in /proc, that
provide a mmap interface into the pci card's resource.  This is nothing
new...

thanks,

greg k-h