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x86: disable intel_iommu support by default 

Due to recurring issues with DMAR support on certain platforms.
There's a number of filesystem corruption incidents reported:

  https://bugzilla.redhat.com/show_bug.cgi?id=479996
  http://bugzilla.kernel.org/show_bug.cgi?id=12578

Provide a Kconfig option to change whether it is enabled by
default.

If disabled, it can still be reenabled by passing intel_iommu=on to the
kernel. Keep the .config option off by default.

Signed-off-by: Kyle McMartin <kyle@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-By: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Kyle McMartin 2009-02-04 14:29:19 -08:00 committed by Ingo Molnar
parent b534816b55
commit 0cd5c3c80a
3 changed files with 24 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
Documentation/kernel-parameters.txt
View File

@ -937,6 +937,8 @@ and is between 256 and 4096 characters. It is defined in the file
intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
on
Enable intel iommu driver.
off
Disable intel iommu driver.
igfx_off [Default Off]

11
arch/x86/Kconfig
View File

@ -1802,6 +1802,17 @@ config DMAR
and include PCI device scope covered by these DMA
remapping devices.
config DMAR_DEFAULT_ON
def_bool n
prompt "Enable DMA Remapping Devices by default"
depends on DMAR
help
Selecting this option will enable a DMAR device at boot time if
one is found. If this option is not selected, DMAR support can
be enabled by passing intel_iommu=on to the kernel. It is
recommended you say N here while the DMAR code remains
experimental.
config DMAR_GFX_WA
def_bool y
prompt "Support for Graphics workaround"

14
drivers/pci/intel-iommu.c
View File

@ -268,7 +268,12 @@ static long list_size;
static void domain_remove_dev_info(struct dmar_domain *domain);
int dmar_disabled;
#ifdef CONFIG_DMAR_DEFAULT_ON
int dmar_disabled = 0;
#else
int dmar_disabled = 1;
#endif /*CONFIG_DMAR_DEFAULT_ON*/
static int __initdata dmar_map_gfx = 1;
static int dmar_forcedac;
static int intel_iommu_strict;
@ -284,9 +289,12 @@ static int __init intel_iommu_setup(char *str)
if (!str)
return -EINVAL;
while (*str) {
if (!strncmp(str, "off", 3)) {
if (!strncmp(str, "on", 2)) {
dmar_disabled = 0;
printk(KERN_INFO "Intel-IOMMU: enabled\n");
} else if (!strncmp(str, "off", 3)) {
dmar_disabled = 1;
printk(KERN_INFO"Intel-IOMMU: disabled\n");
printk(KERN_INFO "Intel-IOMMU: disabled\n");
} else if (!strncmp(str, "igfx_off", 8)) {
dmar_map_gfx = 0;
printk(KERN_INFO