Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Thu, 27 Oct 2022 12:23:41 -0700
From:   Davidlohr Bueso <dave@stgolabs.net>
To:     Dave Hansen <dave.hansen@intel.com>
Cc:     Dan Williams <dan.j.williams@intel.com>, linux-cxl@vger.kernel.org,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org,
        "H. Peter Anvin" <hpa@zytor.com>,
        Andy Lutomirski <luto@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>, nvdimm@lists.linux.dev,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4] memregion: Add cpu_cache_invalidate_memregion()
 interface
Message-ID: <20221027192341.flsnbnmptd4t32ki@offworld>
References: <166672803035.2801111.9244172033971411169.stgit@dwillia2-xfh.jf.intel.com>
 <3ce6ef93-2f47-eda3-f974-0cfea7f43766@intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Disposition: inline
In-Reply-To: <3ce6ef93-2f47-eda3-f974-0cfea7f43766@intel.com>
User-Agent: NeoMutt/20220429
Precedence: bulk

On Thu, 27 Oct 2022, Dave Hansen wrote:

>> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
>> index 67745ceab0db..b68661d0633b 100644
>> --- a/arch/x86/Kconfig
>> +++ b/arch/x86/Kconfig
>> @@ -69,6 +69,7 @@ config X86
>>	select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
>>	select ARCH_HAS_ACPI_TABLE_UPGRADE	if ACPI
>>	select ARCH_HAS_CACHE_LINE_SIZE
>> +	select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION  if X86_64
>
>What is 64-bit only about this?
>
>I don't expect to have a lot of NVDIMMs or CXL devices on 32-bit
>kernels, but it would be nice to remove this if it's not strictly
>needed.  Or, to add a changelog nugget that says:
>
>	Restrict this to X86_64 kernels.  It would probably work on 32-
>	bit, but there is no practical reason to use 32-bit kernels and
>	no one is testing them.

Yes, this was to further limit the potential users.