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Subject: RE: [RFC PATCH v7 00/12] memory: scrub: introduce subsystem +
 CXL/ACPI-RAS2 drivers
Thread-Topic: [RFC PATCH v7 00/12] memory: scrub: introduce subsystem +
 CXL/ACPI-RAS2 drivers
Thread-Index: AQHaZm8buLMwjFZAQ0uEYAlft3jKNLEYHRCAgAAZKjA=
Date: Fri, 23 Feb 2024 17:57:26 +0000
Message-ID:
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References: <20240223143723.1574-1-shiju.jose@huawei.com>
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[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.kerne=
l.org; linux-mm@kvack.org; dan.j.williams@intel.com; dave@stgolabs.net; dav=
e.jiang@intel.com; alison.schofield@intel.com; vishal.l.verma@intel.com; ir=
a.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@googl=
e.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; naoy=
a.horiguchi@nec.com; james.morse@arm.com; jthoughton@google.com; somasundar=
am.a@hpe.com; erdemaktas@google.com; pgonda@google.com; duenwen@google.com;=
 mike.malvestuto@intel.com; gthelen@google.com; wschwartz@amperecomputing.c=
om; dferguson@amperecomputing.com; tanxiaofei@huawei.com; prime.zeng@hisili=
con.com; kangkang.shen@futurewei.com; wanghuiqiang@huawei.com; linuxarm@hua=
wei.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 or=
der to control memory scrub.  RAS2 has some other uses this driver isn't to=
uching on.

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

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

Jonathan