Re: [PATCH] resource: allow MMIO exclusivity for device drivers

From: Jesse Barnes
Date: Mon Dec 01 2008 - 15:29:18 EST

On Sunday, November 23, 2008 1:03 pm Arjan van de Ven wrote:
> From 18cafd344e3de33b5e4feddac5657c1f5fed2d56 Mon Sep 17 00:00:00 2001
> From: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
> Date: Wed, 22 Oct 2008 19:55:31 -0700
> Subject: [PATCH] resource: allow MMIO exclusivity for device drivers
> Device drivers that use pci_request_regions() (and similar APIs) have a
> reasonable expectation that they are the only ones accessing their device.
> As part of the e1000e hunt, we were afraid that some userland (X or some
> bootsplash stuff) was mapping the MMIO region that the driver thought it
> had exclusively via /dev/mem or via various sysfs resource mappings.
> This patch adds the option for device drivers to cause their reserved
> regions to the "banned from /dev/mem use" list, so now both kernel memory
> and device-exclusive MMIO regions are banned.
> NOTE: This is only active when CONFIG_STRICT_DEVMEM is set.
> In addition to the config option, a kernel parameter iomem=relaxed is
> provided for the cases where developers want to diagnose, in the field,
> drivers issues from userspace.
> Reviewed-by: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
> Signed-off-by: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>

Applied to my linux-next branch, thanks Arjan & Matthew.

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