RE: [RFC PATCH v7 00/12] memory: scrub: introduce subsystem + CXL/ACPI-RAS2 drivers

From: "Duran, Leo" <leo.duran@amd.com>
To: Jonathan Cameron <Jonathan.Cameron@Huawei.com>,
	Borislav Petkov <bp@alien8.de>
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Subject: RE: [RFC PATCH v7 00/12] memory: scrub: introduce subsystem + CXL/ACPI-RAS2 drivers
Date: Fri, 23 Feb 2024 17:57:26 +0000	[thread overview]
Message-ID: <BN7PR12MB2644C263D85DBE3DD6431B42F9552@BN7PR12MB2644.namprd12.prod.outlook.com> (raw)
In-Reply-To: <20240223162551.000013ec@Huawei.com>

[AMD Official Use Only - General]

BTW, what is the encoding (units) of the 8-bit "scrub rate"?
(the ACPI spec does not seem to define that detail)

Thanks,
Leo.

-----Original Message-----
From: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
Sent: Friday, February 23, 2024 11:26 AM
To: Borislav Petkov <bp@alien8.de>
Cc: shiju.jose@huawei.com; linux-cxl@vger.kernel.org; linux-acpi@vger.kernel.org; linux-mm@kvack.org; dan.j.williams@intel.com; dave@stgolabs.net; dave.jiang@intel.com; alison.schofield@intel.com; vishal.l.verma@intel.com; ira.weiny@intel.com; linux-edac@vger.kernel.org; linux-kernel@vger.kernel.org; david@redhat.com; Sridharan, Vilas <Vilas.Sridharan@amd.com>; Duran, Leo <leo.duran@amd.com>; Ghannam, Yazen <Yazen.Ghannam@amd.com>; rientjes@google.com; jiaqiyan@google.com; tony.luck@intel.com; Grimm, Jon <Jon.Grimm@amd.com>; dave.hansen@linux.intel.com; rafael@kernel.org; lenb@kernel.org; naoya.horiguchi@nec.com; james.morse@arm.com; jthoughton@google.com; somasundaram.a@hpe.com; erdemaktas@google.com; pgonda@google.com; duenwen@google.com; mike.malvestuto@intel.com; gthelen@google.com; wschwartz@amperecomputing.com; dferguson@amperecomputing.com; tanxiaofei@huawei.com; prime.zeng@hisilicon.com; kangkang.shen@futurewei.com; wanghuiqiang@huawei.com; linuxarm@huawei.com
Subject: Re: [RFC PATCH v7 00/12] memory: scrub: introduce subsystem + CXL/ACPI-RAS2 drivers

On Fri, 23 Feb 2024 16:42:51 +0100
Borislav Petkov <bp@alien8.de> wrote:

> On Fri, Feb 23, 2024 at 10:37:11PM +0800, shiju.jose@huawei.com wrote:
> > CXL patrol scrub and DDR5 ECS and ACPI RAS2 HW based memory patrol
> > scrub features are added as use cases for the scrub subsystem to
> > expose the scrub controls to the user.
>
> WTH is a RAS2 driver and where is the RAS1 driver?
>
Odd ACPI naming.  RASF (which is very limited) was replaced by RAS2.

Both are ACPI tables that describe the Platform Communication Channels
(mailbox) + provide a definition of the protocol that is sent over it in order to control memory scrub.  RAS2 has some other uses this driver isn't touching on.

So in short, it's an ACPI spec defined interface for controlling Memory Scrub engines.

https://uefi.org/specs/ACPI/6.5/05_ACPI_Software_Programming_Model.html#acpi-ras2-feature-table-ras2

Jonathan