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Date:   Fri, 28 Jan 2022 15:51:56 -0800
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To:     Ira Weiny <ira.weiny@intel.com>
Cc:     Dave Hansen <dave.hansen@linux.intel.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Fenghua Yu <fenghua.yu@intel.com>,
        Rick Edgecombe <rick.p.edgecombe@intel.com>,
        linux-kernel@vger.kernel.org
References: <20220127175505.851391-1-ira.weiny@intel.com>
 <20220127175505.851391-7-ira.weiny@intel.com>
 <9c4a8275-236d-67b6-07f9-5e46f66396c0@intel.com>
 <20220128231015.GK785175@iweiny-DESK2.sc.intel.com>
From:   Dave Hansen <dave.hansen@intel.com>
Subject: Re: [PATCH V8 06/44] mm/pkeys: Add Kconfig options for PKS
In-Reply-To: <20220128231015.GK785175@iweiny-DESK2.sc.intel.com>
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On 1/28/22 15:10, Ira Weiny wrote:
> This issue is that because PKS users are in kernel only and are not part of the
> architecture specific code there needs to be 2 mechanisms within the Kconfig
> structure.  One to communicate an architectures support PKS such that the user
> who needs it can depend on that config as well as a second to allow that user
> to communicate back to the architecture to enable PKS.

I *think* the point here is to ensure that PKS isn't compiled in unless
it is supported *AND* needed.  You have to have architecture support
(ARCH_HAS_SUPERVISOR_PKEYS) to permit features that depend on PKS to be
enabled.  Then, once one ore more of *THOSE* is enabled,
ARCH_ENABLE_SUPERVISOR_PKEYS comes into play and actually compiles the
feature in.

In other words, there are two things that must happen before the code
gets compiled in:

1. Arch support
2. One or more features to use the arch support