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authorLu Baolu <baolu.lu@linux.intel.com>2019-01-24 10:31:32 +0800
committerJoerg Roedel <jroedel@suse.de>2019-01-30 17:23:58 +0100
commit8950dcd83ae7d62bdc2a60507949acebd85399f2 (patch)
treef16ce662f31aa59f682a3ae52b0ad8e1f3fa1fa0 /Documentation
parent9825bd94e3a2baae1f4874767ae3a7d4c049720e (diff)
iommu/vt-d: Leave scalable mode default off
Commit 765b6a98c1de3 ("iommu/vt-d: Enumerate the scalable mode capability") enables VT-d scalable mode if hardware advertises the capability. As we will bring up different features and use cases to upstream in different patch series, it will leave some intermediate kernel versions which support partial features. Hence, end user might run into problems when they use such kernels on bare metals or virtualization environments. This leaves scalable mode default off and end users could turn it on with "intel-iommu=sm_on" only when they have clear ideas about which scalable features are supported in the kernel. Cc: Liu Yi L <yi.l.liu@intel.com> Cc: Jacob Pan <jacob.jun.pan@linux.intel.com> Suggested-by: Ashok Raj <ashok.raj@intel.com> Suggested-by: Kevin Tian <kevin.tian@intel.com> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> Signed-off-by: Joerg Roedel <jroedel@suse.de>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/admin-guide/kernel-parameters.txt7
1 files changed, 3 insertions, 4 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index b799bcf67d7b..858b6c0b9a15 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1696,12 +1696,11 @@
By default, super page will be supported if Intel IOMMU
has the capability. With this option, super page will
not be supported.
- sm_off [Default Off]
- By default, scalable mode will be supported if the
+ sm_on [Default Off]
+ By default, scalable mode will be disabled even if the
hardware advertises that it has support for the scalable
mode translation. With this option set, scalable mode
- will not be used even on hardware which claims to support
- it.
+ will be used on hardware which claims to support it.
tboot_noforce [Default Off]
Do not force the Intel IOMMU enabled under tboot.
By default, tboot will force Intel IOMMU on, which