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authorArjan van de Ven <arjan@linux.intel.com>2008-10-22 19:55:31 -0700
committerJesse Barnes <jbarnes@virtuousgeek.org>2009-01-07 11:12:32 -0800
commite8de1481fd7126ee9e93d6889da6f00c05e1e019 (patch)
tree3e0e564f6aff2f8f0f66bdf37dc2eb87d6e17cde /Documentation
parent23616941914917cf25b94789856b5326b68d8ee8 (diff)
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@linux.intel.com> Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/kernel-parameters.txt4
1 files changed, 4 insertions, 0 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 0b3f6711d2f..0072fabb1dd 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -918,6 +918,10 @@ and is between 256 and 4096 characters. It is defined in the file
inttest= [IA64]
+ iomem= Disable strict checking of access to MMIO memory
+ strict regions from userspace.
+ relaxed
+
iommu= [x86]
off
force