Re: UIO: missing resource mapping

From: Michael S. Tsirkin
Date: Fri Jul 13 2012 - 09:22:14 EST


On Fri, Jul 13, 2012 at 10:09:15AM +0200, Dominic Eschweiler wrote:
> Am Freitag, den 13.07.2012, 02:16 +0300 schrieb Michael S. Tsirkin:
> > My concern was people will ask for more and more stuff that pci
> > sysfs already has.
> > If we do add these is there a way to not duplicate code from pci?
>
> I have some concerns about the placing for the BAR mapping code inside
> the kernel. The point is, that sysfs currently makes it possible to map
> BARs of all card which are handled by any driver. This is fine in case
> of UIO, because it is intended that a user-space program maps BARs, but
> it is also possible to map BARs that are already handle by a kernel
> driver. It i therefore possible to jam the system by confusing sysfs
> entries.
>
> I don't know which implications this has, but I would move the BAR
> mapping capabilities completely to UIO. This should ensure that only
> BARs can be mapped, which are handled by UIO and no other kernel-space
> driver.

Could you give an example of the problem? How do you bind
both UIO and another driver to the same device?

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