RE: [PATCH v10 0/3] ACPI: Add support for ACPI RAS2 feature table

[Shiju Jose <shiju.jose@huawei.com>]

>-----Original Message-----
>From: Daniel Ferguson <danielf@os.amperecomputing.com>
>Sent: 08 August 2025 17:39
>To: Shiju Jose <shiju.jose@huawei.com>; rafael@kernel.org; bp@alien8.de;
>akpm@linux-foundation.org; rppt@kernel.org;
>dferguson@amperecomputing.com; linux-edac@vger.kernel.org; linux-
>acpi@vger.kernel.org; linux-mm@kvack.org; linux-doc@vger.kernel.org;
>tony.luck@intel.com; lenb@kernel.org; leo.duran@amd.com;
>Yazen.Ghannam@amd.com; mchehab@kernel.org
>Cc: Jonathan Cameron <jonathan.cameron@huawei.com>; Linuxarm
><linuxarm@huawei.com>; rientjes@google.com; jiaqiyan@google.com;
>Jon.Grimm@amd.com; dave.hansen@linux.intel.com;
>naoya.horiguchi@nec.com; james.morse@arm.com; jthoughton@google.com;
>somasundaram.a@hpe.com; erdemaktas@google.com; pgonda@google.com;
>duenwen@google.com; gthelen@google.com;
>wschwartz@amperecomputing.com; wbs@os.amperecomputing.com;
>nifan.cxl@gmail.com; tanxiaofei <tanxiaofei@huawei.com>; Zengtao (B)
><prime.zeng@hisilicon.com>; Roberto Sassu <roberto.sassu@huawei.com>;
>kangkang.shen@futurewei.com; wanghuiqiang <wanghuiqiang@huawei.com>
>Subject: Re: [PATCH v10 0/3] ACPI: Add support for ACPI RAS2 feature table
>
>> Changes
>> =======
>> v9 -> v10:
>> 1. Use pcc_chan->shmem instead of
>>    acpi_os_ioremap(pcc_chan->shmem_base_addr,...) as it was
>>    acpi_os_ioremap internally by the PCC driver to pcc_chan->shmem.
>>
>> 2. Changes required for the Ampere Computing system where uses a single
>>    PCC channel for RAS2 memory features across all NUMA domains. Based on
>the
>>    requirements from by Daniel on V9
>>    https://lore.kernel.org/all/547ed8fb-d6b7-4b6b-a38b-
>bf13223971b1@os.amperecomputing.com/
>>    and discussion with Jonathan.
>> 2.1 Add node_to_range lookup facility to numa_memblks. This is to retrieve
>the lowest
>>     physical continuous memory range of the memory associated with a NUMA
>domain.
>> 2.2. Set requested addr range to the memory region's base addr and size
>>    while send RAS2 cmd GET_PATROL_PARAMETER
>>    in functions ras2_update_patrol_scrub_params_cache() &
>>    ras2_get_patrol_scrub_running().
>> 2.3. Split struct ras2_mem_ctx into struct ras2_mem_ctx_hdr and struct
>ras2_pxm_domain
>>    to support cases, uses a single PCC channel for RAS2 scrubbers across all
>NUMA
>>    domains and PCC channel per RAS2 scrub instance. Provided ACPI spec
>define single
>>    memory scrub per NUMA domain.
>> 2.4. EDAC feature sysfs folder for RAS2 changed from "acpi_ras_memX" to
>"acpi_ras_mem_idX"
>>    because memory scrub instances across all NUMA domains would present
>under
>>    "acpi_ras_mem_id0" when a system uses a single PCC channel for RAS2
>scrubbers across
>>    all NUMA domains etc.
>> 2.5. Removed Acked-by: Rafael from patch [2], because of the several above
>changes from v9.
>
>A) We have tested the changes you have made, and they work. Thank you.
Thanks for verifying the changes.
>
>B) In the early days of this patch series, as we began developing our firmware to
>keep pace with your development of this driver, we indeed only had one PCC
>channel shared across all proximity domains. Since then, we have evolved our
>firmware to have a PCC channel per proximity domain. It didn't seem important
>to mention this to you since the supporting code was minimal. However, with
>this latest update (v10), it has become apparent that you have taken extra
>efforts to preserve this accommodation. So, now I'm obliged to say that we no
>longer need this accommodation. If it would help make things cleaner, and
>require less explanation, we support the removal of this legacy, non-compliant
>accommodation.
Thanks Daniel for sharing information. I will remove workarounds previously added for
non-compliant case and will simplify the code.
>
>Respectfully,
>~Daniel
>
>
Thanks,
Shiju