From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3xntyY0FPczDqYV for ; Thu, 7 Sep 2017 18:33:40 +1000 (AEST) Message-ID: <1504773212.12628.26.camel@kernel.crashing.org> Subject: Re: UIO memmap of PCi devices not working? From: Benjamin Herrenschmidt To: Joakim Tjernlund , "linuxppc-dev@lists.ozlabs.org" Date: Thu, 07 Sep 2017 18:33:32 +1000 In-Reply-To: <1504768943.27247.149.camel@infinera.com> References: <1504711235.27247.110.camel@infinera.com> <1504768612.12628.19.camel@kernel.crashing.org> <1504768943.27247.149.camel@infinera.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, 2017-09-07 at 07:22 +0000, Joakim Tjernlund wrote: > On Thu, 2017-09-07 at 17:16 +1000, Benjamin Herrenschmidt wrote: > > On Wed, 2017-09-06 at 15:20 +0000, Joakim Tjernlund wrote: > > > Having problems to mmap PCI UIO devices and stumbeled over this page: > > > http://billfarrow.blogspot.se/2010/09/userspace-access-to-pci-memory.html > > > it claims some adjustments are needed for UIO mmap over PCI to work. > > > These are #if 0 ATM and trying to enable them fails build. > > > > > > Can this be fixed to at least build again ? > > > The reason for having #if 0 in the first place appears to be old X servers, > > > is that still true? Can the special casing be removed now? > > > > This article seems out of date... I *think* things should work without > > change by just mmap'ing the appropriate sysfs files. I'm not sure why > > the author thought that had to be ifdef'ed out... > > Isn't that what the article is doing(mmaping sysfs files)? > And the article author is #ifdefing it back, not out. Yes sorry that's what I meant. It should work as-is. > > > > Let me know if you have problems. > > Sure, we still are looking > > > > > As far as I know, the generic code will call pci_resource_to_user() > > which on powerpc will return a physical address that already includes > > the offset, which is why we don't later add it. > > > > Now we could probably tear all that out and use the new generic code > > instead as I *think* X has (very) long been fixed but I'd have to spend > > some time triple checking and testing on old HW which I don't have the > > bandwidth for right now. > > Could you fixup the code which is now #if 0 ? I wan't to test the > difference and I not sure how to fix the build problem after changing > those two #if 0 to #if 1 > Even better if they could be a CONFIG option instead. Hrm it's tricky, you shouldn't just turn that ifdef back on without also changing pci_resource_to_user(). I'm not sure exactly what's going on in your case, if you have a problem can you add printk to instrument ? Cheers, Ben.