linux-kernel - Re: [RFC PATCH 3/9] Documentation/scrub-configure.rst: Add documentation for scrub driver

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Date:   Mon, 18 Sep 2023 09:23:50 +0200
From:   David Hildenbrand <david@...hat.com>
To:     shiju.jose@...wei.com, linux-acpi@...r.kernel.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc:     rafael@...nel.org, lenb@...nel.org, naoya.horiguchi@....com,
        tony.luck@...el.com, james.morse@....com,
        dave.hansen@...ux.intel.com, jiaqiyan@...gle.com,
        jthoughton@...gle.com, somasundaram.a@....com,
        erdemaktas@...gle.com, pgonda@...gle.com, rientjes@...gle.com,
        duenwen@...gle.com, Vilas.Sridharan@....com,
        mike.malvestuto@...el.com, gthelen@...gle.com, linuxarm@...wei.com,
        jonathan.cameron@...wei.com, tanxiaofei@...wei.com,
        prime.zeng@...ilicon.com
Subject: Re: [RFC PATCH 3/9] Documentation/scrub-configure.rst: Add
 documentation for scrub driver

On 15.09.23 19:28, shiju.jose@...wei.com wrote:
> From: Shiju Jose <shiju.jose@...wei.com>
> 
> Add documentation for scrub driver, supports configure scrub parameters,
> in Documentation/scrub-configure.rst
> 
> Signed-off-by: Shiju Jose <shiju.jose@...wei.com>
> ---
>   Documentation/scrub-configure.rst | 55 +++++++++++++++++++++++++++++++
>   1 file changed, 55 insertions(+)
>   create mode 100644 Documentation/scrub-configure.rst
> 
> diff --git a/Documentation/scrub-configure.rst b/Documentation/scrub-configure.rst
> new file mode 100644
> index 000000000000..9f8581b88788
> --- /dev/null
> +++ b/Documentation/scrub-configure.rst
> @@ -0,0 +1,55 @@
> +==========================
> +Scrub subsystem driver
> +==========================
> +
> +Copyright (c) 2023 HiSilicon Limited.
> +
> +:Author:   Shiju Jose <shiju.jose@...wei.com>
> +:License:  The GNU Free Documentation License, Version 1.2
> +          (dual licensed under the GPL v2)
> +:Original Reviewers:
> +
> +- Written for: 6.7
> +- Updated for:
> +
> +Introduction
> +------------
> +The scrub subsystem driver provides the interface for configure the

"... interface for configuring memory scrubbers in the system."

are we only configuring firmware/hw-based memory scrubbing? I assume so.

> +parameters of memory scrubbers in the system. The scrub device drivers
> +in the system register with the scrub configure subsystem.

Maybe say a few words what memory scrubbing is, and what it is used for.

> +
> +The scrub configure driver exposes the scrub controls to the user
> +via sysfs.
> +
> +The File System
> +---------------
> +
> +The configuration parameters of the registered scrubbers could be
> +accessed via the /sys/class/scrub/scrubX/regionN/
> +
> +sysfs
> +-----
> +
> +Sysfs files are documented in
> +`Documentation/ABI/testing/sysfs-class-scrub-configure`.
> +
> +Example
> +-------
> +
> +  The usage takes the form shown in this example::
> +
> +    # echo 0x300000 > /sys/class/scrub/scrub0/region0/addr_base
> +    # echo 0x100000 > /sys/class/scrub/scrub0/region0/addr_size
> +    # cat /sys/class/scrub/scrub0/region0/speed_available
> +    # 1-60
> +    # echo 25 > /sys/class/scrub/scrub0/region0/speed
> +    # echo 1 > /sys/class/scrub/scrub0/region0/enable
> +
> +    # cat /sys/class/scrub/scrub0/region0/speed
> +    # 0x19

Is it reasonable to return the speed as hex? You set it as dec.

> +    # cat /sys/class/scrub/scrub0/region0/addr_base
> +    # 0x100000

But didn't we set it to 0x300000 ...

> +    # cat /sys/class/scrub/scrub0/region0/addr_size
> +    # 0x200000

... and didn't we set it to 0x100000 ?

Or what's the magic happening here?

> +
> +    # echo 0 > /sys/class/scrub/scrub0/region0/enable

-- 
Cheers,

David / dhildenb