From: Hanjun Guo <guohanjun@huawei•com>
To: John Garry <john.garry@huawei•com>, <catalin.marinas@arm•com>,
<will@kernel•org>, <rjw@rjwysocki•net>, <lenb@kernel•org>,
<robert.moore@intel•com>, <erik.schmauss@intel•com>,
<sudeep.holla@arm•com>, <rrichter@marvell•com>,
<jeremy.linton@arm•com>
Cc: gregkh@linuxfoundation•org, linux-kernel@vger•kernel.org,
linuxarm@huawei•com, linux-acpi@vger•kernel.org,
linux-arm-kernel@lists•infradead.org, wanghuiqiang@huawei•com
Subject: Re: [RFC PATCH 0/3] ACPI, arm64: Backport for ACPI PPTT 6.3 thread flag for stable 4.19.x
Date: Fri, 11 Oct 2019 08:53:32 +0800 [thread overview]
Message-ID: <ed2ce119-dd68-131c-72e9-e95fc8fc6465@huawei.com> (raw)
In-Reply-To: <1570714192-236724-1-git-send-email-john.garry@huawei.com>
Hi John,
On 2019/10/10 21:29, John Garry wrote:
> This series is a backport of the ACPI PPTT 6.3 thread flag feature for
> supporting arm64 systems.
>
> The background is that some arm64 implementations are broken, in that they
> incorrectly advertise that a CPU is mutli-threaded, when it is not - the
> HiSilicon Taishanv110 rev 2, aka tsv110, being an example.
>
> This leads to the system topology being incorrect. The reason being that
> arm64 topology code uses a combination of ACPI PPTT (Processor Properties
> Topology Table) and the system MPIDR (Multiprocessor Affinity Register) MT
> bit to determine the topology.
>
> Until ACPI 6.3, the PPTT did not have any method to determine whether
> a CPU was multi-threaded, so only the MT bit is used - hence the
> broken topology for some systems.
>
> In ACPI 6.3, a PPTT thread flag was introduced, which - when supported -
> would be used by the kernel to determine really if a CPU is multi-threaded
> or not, so that we don't get incorrect topology.
Thanks for doing this, and this patch set fix my CPU topology issue
in 4.19 kernel with updated firmware.
>
> Note: I'm sending this as an RFC before sending to stable proper. I also
> have a 5.2 and 5.3 backport which are almost the same, and only
> significant change being that the ACPICA patch is not required.
5.2 stable was end of life, so only 4.19 and 5.3 are needed I think.
Thanks
Hanjun
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prev parent reply other threads:[~2019-10-11 0:54 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-10 13:29 [RFC PATCH 0/3] ACPI, arm64: Backport for ACPI PPTT 6.3 thread flag for stable 4.19.x John Garry
2019-10-10 13:29 ` [RFC PATCH 1/3] ACPICA: ACPI 6.3: PPTT add additional fields in Processor Structure Flags John Garry
2019-10-10 14:22 ` Moore, Robert
2019-10-10 14:28 ` John Garry
2019-10-10 13:29 ` [RFC PATCH 2/3] ACPI/PPTT: Add support for ACPI 6.3 thread flag John Garry
2019-10-10 13:29 ` [RFC PATCH 3/3] arm64: topology: Use PPTT to determine if PE is a thread John Garry
2019-10-11 0:53 ` Hanjun Guo [this message]
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