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| author | Lu Baolu <baolu.lu@linux.intel.com> | 2019-01-24 10:31:32 +0800 |
|---|---|---|
| committer | Joerg Roedel <jroedel@suse.de> | 2019-01-30 17:23:58 +0100 |
| commit | 8950dcd83ae7d62bdc2a60507949acebd85399f2 (patch) | |
| tree | f16ce662f31aa59f682a3ae52b0ad8e1f3fa1fa0 /Documentation | |
| parent | 9825bd94e3a2baae1f4874767ae3a7d4c049720e (diff) | |
| download | linux-8950dcd83ae7d62bdc2a60507949acebd85399f2.tar.gz | |
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.txt | 7 |
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 |