Re: [PATCH 1/1] iommu/vt-d: Leave scalable mode default off

From: Joerg Roedel
Date: Wed Jan 30 2019 - 11:24:38 EST

On Thu, Jan 24, 2019 at 10:31:32AM +0800, Lu Baolu wrote:
> 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@xxxxxxxxx>
> Cc: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> Suggested-by: Ashok Raj <ashok.raj@xxxxxxxxx>
> Suggested-by: Kevin Tian <kevin.tian@xxxxxxxxx>
> Signed-off-by: Lu Baolu <>

Applied to iommu/fixes, thanks.