linux-kernel - Re: [PATCH v3 1/3] arch/x86: Rename config X86_INTEL_MEMORY_PROTECTION

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Date:   Tue, 12 May 2020 09:57:22 -0500
From:   Babu Moger <babu.moger@....com>
To:     Dave Hansen <dave.hansen@...el.com>, corbet@....net,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, hpa@...or.com,
        pbonzini@...hat.com, sean.j.christopherson@...el.com
Cc:     x86@...nel.org, vkuznets@...hat.com, wanpengli@...cent.com,
        jmattson@...gle.com, joro@...tes.org, dave.hansen@...ux.intel.com,
        luto@...nel.org, peterz@...radead.org, mchehab+samsung@...nel.org,
        changbin.du@...el.com, namit@...are.com, bigeasy@...utronix.de,
        yang.shi@...ux.alibaba.com, asteinhauser@...gle.com,
        anshuman.khandual@....com, jan.kiszka@...mens.com,
        akpm@...ux-foundation.org, steven.price@....com,
        rppt@...ux.vnet.ibm.com, peterx@...hat.com,
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        robin.murphy@....com, ira.weiny@...el.com, keescook@...omium.org,
        jgross@...e.com, andrew.cooper3@...rix.com,
        pawan.kumar.gupta@...ux.intel.com, fenghua.yu@...el.com,
        vineela.tummalapalli@...el.com, yamada.masahiro@...ionext.com,
        sam@...nborg.org, acme@...hat.com, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH v3 1/3] arch/x86: Rename config
 X86_INTEL_MEMORY_PROTECTION_KEYS to generic x86



On 5/11/20 6:44 PM, Dave Hansen wrote:
> On 5/11/20 4:32 PM, Babu Moger wrote:
>> AMD's next generation of EPYC processors support the MPK (Memory
>> Protection Keys) feature.
>>
>> So, rename X86_INTEL_MEMORY_PROTECTION_KEYS to X86_MEMORY_PROTECTION_KEYS.
>>
>> No functional changes.
>>
>> AMD documentation for MPK feature is available at "AMD64 Architecture
>> Programmer’s Manual Volume 2: System Programming, Pub. 24593 Rev. 3.34,
>> Section 5.6.6 Memory Protection Keys (MPK) Bit". Documentation can be
>> obtained at the link below.

I will remove this text. This is not too relevant here.

> 
> I was hoping to see at least *some* justification in this changelog.  Do
> you think having "INTEL_" will confuse users?  Is there some technical
> merit to this change?
> 
> The naming churn is an obviously bad, not technically necessary change.

Yes. Technically not necessary. But can cause some confusion on non-intel
platforms.

> 
>> +config X86_MEMORY_PROTECTION_KEYS
>> +	# Note: This is an intermediate change to avoid config prompt to
>> +	# the users. Eventually, the option X86_INTEL_MEMORY_PROTECTION_KEYS
>> +	# should be changed to X86_MEMORY_PROTECTION_KEYS permanently after
>> +	# few kernel revisions.
>> +	def_bool X86_INTEL_MEMORY_PROTECTION_KEYS
> 
> "after a few kernel revisions" is code for "never". :)
> 
> Could we put an explicit date on this, please?  One year seems roughly
> right.  Or, maybe "after the v5.10" release, so that this will approach
> will make into at least one LTS kernel.
> 
> Maybe:
> 
> # Set the "INTEL_"-free option whenever the "INTEL_" one is set.
> # The "INTEL_" one should be removed and replaced by this option after
> # 5.10.  This avoids exposing most 'oldconfig' users to this churn.
> 
Yes, this should work.