From mboxrd@z Thu Jan 1 00:00:00 1970 From: josh@joshtriplett.org Subject: Re: [PATCH v4 10/10] x86: Support compiling out userspace IO (iopl and ioperm) Date: Mon, 3 Nov 2014 08:45:39 -0800 Message-ID: <20141103164539.GA18104@cloud> References: <20141103121049.2f0c81a9@alan.etchedpixels.co.uk> <20141103141357.GC21818@thin> <20141103152748.327032f8@alan.etchedpixels.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20141103152748.327032f8@alan.etchedpixels.co.uk> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: One Thousand Gnomes Cc: Kees Cook , x86@kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Ingo Molnar , "H. Peter Anvin" , Thomas Gleixner List-Id: virtualization@lists.linuxfoundation.org On Mon, Nov 03, 2014 at 03:27:48PM +0000, One Thousand Gnomes wrote: > > > This isn't unreasonable but there are drivers with userspace helpers that > > > use iopl/ioperm type functionality where you should be doing a SELECT of > > > X86_IOPORT. The one that comes to mind is the uvesa driver. From a quick > > > scan it may these days be the only mainstream one that needs the select > > > adding. > > > > Should kernel drivers really express dependencies that only their > > (current instances of) corresponding userspace components need? > > Something seems wrong about that. > > uvesafb will always need X86_IOPORT. It's kind of implicit in the design. > I'm not suggesting that fbdev should select X86_IOPORT but in the uvesafb > case at least it's completely useless to have one and not the other. OK, fair enough. Do you want the patch series respun to add that select in patch 10/10, or would you consider it sufficient to add that in a followup patch, since the kernel will build and boot either way (so it won't break bisection)? Related to that: Is it intentional that FB_UVESA doesn't depend on X86, even though FB_VESA does? Does v86d run on non-x86 hardware via emulation? If so, should FB_UVESA have "select X86_IOPORT if X86"? - Josh Triplett