From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758441AbYGJWKM (ORCPT ); Thu, 10 Jul 2008 18:10:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754297AbYGJWJ6 (ORCPT ); Thu, 10 Jul 2008 18:09:58 -0400 Received: from mercury.realtime.net ([205.238.132.86]:39744 "EHLO ruth.realtime.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754052AbYGJWJ5 (ORCPT ); Thu, 10 Jul 2008 18:09:57 -0400 X-Greylist: delayed 971 seconds by postgrey-1.27 at vger.kernel.org; Thu, 10 Jul 2008 18:09:57 EDT In-Reply-To: <48768018.2070704@hhs.nl> References: <48768018.2070704@hhs.nl> Mime-Version: 1.0 (Apple Message framework v624) Content-Type: text/plain; charset=US-ASCII; format=flowed Message-Id: Content-Transfer-Encoding: 7bit Cc: Samuel Ortiz , linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org, lm-sensors@lm-sensors.org From: Milton Miller Subject: Re: [lm-sensors] [RFC] (almost) booting allyesconfig -- please don't poke super-io without request_region Date: Thu, 10 Jul 2008 16:51:33 -0500 To: Hans de Goede X-Mailer: Apple Mail (2.624) X-Originating-IP: 216.126.174.36 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Jul 10, 2008, at 4:33 PM, Hans de Goede wrote: > Milton Miller wrote: >> After the following patch to mark the isa region busy and applying a >> few >> patches[1], I was able to kexec boot into an all-yes-config kernel >> from linux-next, with the following KCONFIG_ALLCONFIG file: ... >> While the first two might not be required, and the third is just >> selecting the right platform, it would be nice to get the drivers >> to play as well as the rest of the kernel. >> The drivers all are for super-io chips, either irda/FIR drivers or >> hwmon, >> and poke at isa ports without checking request_region. > > Erm, > > The superio sensor drivers only poke the superio chip registers > without request region during the probe phase, iow they try to detect > the chip, using a widely document and standardized (part of isa pnp > AFAIK) procedure on standardized ports. > > Let me try to explain a bit about superio chips, they have 2 superio > control registers (an index and data register) with which things like > a manufacturer and device id can be read, besides these id registers > they also have a set of registers with config for different logical > devices. Once the id is matched, the driver knows which logical device > config to read, reads a (different) isa base address + range from the > logical device config, and then does a request_region on the region > actually used by the logical device. > > The superio control registers are thus a sort of pci configuration > space if you want, doing a request_region on these is not such a good > idea, as multiple drivers (for different logical devices within the > superio device) may use these, so trying to gain exclusive access will > lead to troubles. > > I hope with this info about the problem space, that you maybe have a > suggestion on howto fix this? > My point is that they are probing without even knowing that a such a IO range exists. These are the only drivers left in the tree that still do this. (At least that are not blocked on a powerpc allyesconfig for 64-bit, !CONFIG_VIRT_TO_BUS). One could make a superio driver, and create sub-devices for the IR, I2C, floppy, parallel, etc nodes. I would even accept a check_region (horrors!), it would impove the situation. But most other drivers do this by request_region, probe, then release the region afterwards. Besides, one could argue the superio region should be requested while probing, to prevent other cpus from poking at the super io chip at the same time. Think of it as missing locking. milton