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Date: Thu, 25 May 2017 11:56:04 -0700
Subject: Re: [PATCH v5 07/14] OvmfPkg:IoMmuDxe: Add IoMmuDxe driver
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On 2017-05-25 10:58:45, Laszlo Ersek wrote:
> =

> If you add a patch to the series where you change the DEPEX of
> PciHostBridgeDxe to
> =

>   gEdkiiIoMmuProtocolGuid OR gEdkiiIoMmuAbsentProtocolGuid
> =

> then the maintainer (Ray or Jiewen I think) will likely reject that
> patch, because afterwards, all platforms that include PciHostBridgeDxe
> would suddenly have to produce gEdkiiIoMmuAbsentProtocolGuid, minimally.

I haven't worked with it, but it does appear that feature PCD's can be
used to conditionally add new depex values.

$ git grep -e '|.*Pcd' -- '*.inf'

I'm not sure if that feature works with depex 'OR'.

Regarding IoMmuAbsent or IoMmuDetectionAttempted, they seem similar.

-Jordan