Re: [GIT PATCH] UIO patches for 2.6.21

[Thomas Gleixner]

On Sat, 2007-04-28 at 18:23 -0700, Greg KH wrote:
> On Sat, Apr 28, 2007 at 10:31:37PM +0200, Thomas Gleixner wrote:
> > On Sat, 2007-04-28 at 21:15 +0100, Alan Cox wrote:
> > > > > I have a political question, if I have a user space driver, is my kernel 
> > > > > tainted or not? 
> > > > 
> > > > Surely not. By using the kernel's userspace interface, you create no
> > > > "derived work" of the kernel. See COPYING in the root directory of the 
> > > > kernel sources for details.
> > > 
> > > That only covers normal system calls - but I don't think thats what is
> > > relevant, taints are for debug assistance not politics.
> > > 
> > > I think we should have a taint flag for UIO type drivers. Not for any
> > > licensing or political reason but for the simple fact it means that there
> > > may be other complexities to debugging - and not the same one as a binary
> > > module. Probably we want the same marker for mmap /dev/mem too.
> > 
> > I agree, if we make it entirely clear that the flag is nonpolitical. 
> 
> Hm, I don't know, what makes this different from the fact that we can
> mmap PCI device space today through the proc and sysfs entries?  That's
> how X gets direct access to the hardware for a number of different
> cards, and that's pretty much the same thing as the UIO interface is
> doing.
> 
> Unless you think we should also use the same "taint" flag on those
> accesses too, and if so, I have no objection.

Right, this is just a hint, that something in user space is accessing
the hardware directly. Not a too bad idea, but pretty much useless when
we add X to the picture as it will be set always :)

	tglx


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