linux-kernel - RE: [RFC PATCH v8 01/10] ras: scrub: Add scrub subsystem

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Date: Wed, 8 May 2024 16:59:18 +0000
From: Shiju Jose <shiju.jose@...wei.com>
To: Borislav Petkov <bp@...en8.de>
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Subject: RE: [RFC PATCH v8 01/10] ras: scrub: Add scrub subsystem

>-----Original Message-----
>From: Borislav Petkov <bp@...en8.de>
>Sent: 06 May 2024 11:30
>To: Shiju Jose <shiju.jose@...wei.com>
>Cc: linux-cxl@...r.kernel.org; linux-acpi@...r.kernel.org; linux-
>mm@...ck.org; dan.j.williams@...el.com; dave@...olabs.net; Jonathan
>Cameron <jonathan.cameron@...wei.com>; dave.jiang@...el.com;
>alison.schofield@...el.com; vishal.l.verma@...el.com; ira.weiny@...el.com;
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>Linuxarm <linuxarm@...wei.com>
>Subject: Re: [RFC PATCH v8 01/10] ras: scrub: Add scrub subsystem
>
>On Thu, Apr 25, 2024 at 06:11:13PM +0000, Shiju Jose wrote:
>> It is expected to have multiple RAS-specific functionalities other
>> than scrubbing  in long run.  Most of the classes in the kernel found
>> as  /sys/class/<class-name>/<class-name>X/
>>
>> If not, however /sys/class/ras/<module -name>X/<feature> is more
>> suitable because there are multiple device instances such as cxl
>> devices with scrub control feature.  For example,
>> /sys/class/ras/cxlX/scrub
>
>Make it as user-friendly as possible. cxlX is not as user-friendly as
>
>/sys/class/ras/cxl/<mem_accelerator>
>		  /<fancy_bla_thing>
>
>and so on.
>
>Yes, you can introduce a special category .../ras/cxl/ if there are multiple cxl
>devices which have RAS functionality on them.
Sure.

>
>> Presently underlying hw driver does the check. I think this will
>> become more complex if does in the common rate_store() if we have to
>> check against either a list of possible rates or min and max rates.
>
>Ok.
>
>> >> +DEVICE_ATTR_RW(enable_background);
>> >> +DEVICE_ATTR_RO(name);
>> >> +DEVICE_ATTR_RW(rate);
>> >> +DEVICE_ATTR_RO(rate_available);
>> >
>> >static
>
>Forgot one.
Will correct.

>
>> This is the ras instance id (X) used for scrub control feature,
>> /sys/class/ras/rasX/scrub/
>
>Yeah, as discussed  above.
OK.
>
>> >> +static int __init memory_scrub_control_init(void) {
>> >> +	return class_register(&scrub_class); }
>> >> +subsys_initcall(memory_scrub_control_init);
>> >
>> >You can't just blindly register this thing without checking whether
>> >there are even any hw scrubber devices on the system.
>>
>> I think it happens only when a dependent module as autoloaded based on
>> a scrub device existing with exception of memory scrub control built
>> in and who would build this in?
>
>You think or you know?
We know as I had tested.

>
>--
>Regards/Gruss,
>    Boris.
>
>https://people.kernel.org/tglx/notes-about-netiquette

Thanks,
Shiju