From 0cd5c3c80a0ebd68c08312fa7d8c13149cc61c4c Mon Sep 17 00:00:00 2001
From: Kyle McMartin <kyle@redhat.com>
Date: Wed, 4 Feb 2009 14:29:19 -0800
Subject: [PATCH] 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>
---
Documentation/kernel-parameters.txt | 2 ++
arch/x86/Kconfig | 11 +++++++++++
drivers/pci/intel-iommu.c | 14 +++++++++++---
3 files changed, 24 insertions(+), 3 deletions(-)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index d8362cf9909ec..b182626739ea7 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -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]
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 73f7fe8fd4d1c..9c39095b33fc0 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -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"
diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index 3dfecb20d5e79..f4b7c79023ffe 100644
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -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
--
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