From: Ananth Narayan <ananth.narayan@amd.com>
To: Borislav Petkov <bp@alien8.de>, Dave Hansen <dave.hansen@intel.com>
Cc: K Prateek Nayak <kprateek.nayak@amd.com>,
linux-kernel@vger.kernel.org, rafael@kernel.org, lenb@kernel.org,
linux-acpi@vger.kernel.org, linux-pm@vger.kernel.org,
dave.hansen@linux.intel.com, tglx@linutronix.de, andi@lisas.de,
puwen@hygon.cn, mario.limonciello@amd.com, peterz@infradead.org,
rui.zhang@intel.com, gpiccoli@igalia.com,
daniel.lezcano@linaro.org, gautham.shenoy@amd.com,
Calvin Ong <calvin.ong@amd.com>,
stable@vger.kernel.org, regressions@lists.linux.dev
Subject: Re: [PATCH] ACPI: processor_idle: Skip dummy wait for processors based on the Zen microarchitecture
Date: Thu, 22 Sep 2022 09:28:55 +0530 [thread overview]
Message-ID: <fb54de68-d314-389c-0aff-9363ac2e50b9@amd.com> (raw)
In-Reply-To: <YytrV2UMah8555+s@zn.tnic>
On 22-09-2022 01:21 am, Borislav Petkov wrote:
> On Wed, Sep 21, 2022 at 07:15:07AM -0700, Dave Hansen wrote:
>> In the end, the delay is because of buggy, circa 2006 chipsets? So, we
>> use a CPU vendor specific check to approximate that the chipset is
>> recent and not affected by the bug? If so, is there no better way to
>> check for a newer chipset than this?
>
> So I did some git archeology but that particular addition is in some
> conglomerate, glued-together patch from 2007 which added the cpuidle
> tree:
>
> commit 4f86d3a8e297205780cca027e974fd5f81064780
> Author: Len Brown <len.brown@intel.com>
> Date: Wed Oct 3 18:58:00 2007 -0400
>
> cpuidle: consolidate 2.6.22 cpuidle branch into one patch
In fact, the code has moved around a fair bit and the check in its initial form
goes as far back as ACPI's posting for inclusion in the kernel in March 2002
[1]. We could not find any way of digging further back, yet.
Prior to that, I think the ACPI enablement code was being released independent
of the kernel per https://kernel.org/doc/ols/2004/ols2004v1-pages-121-132.pdf
and was included in Andrew's mm tree for a while.
From https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git
the first tag that contains code with the dummy read is v2.5.7 AFAICS.
Ananth
[1]
https://git.kernel.org/pub/scm/linux/kernel/git/mpe/linux-fullhistory.git/commit/?id=972c16130d9dc182cedcdd408408d9eacc7d6a2d
next prev parent reply other threads:[~2022-09-22 3:59 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-21 6:36 [PATCH] ACPI: processor_idle: Skip dummy wait for processors based on the Zen microarchitecture K Prateek Nayak
2022-09-21 8:47 ` Borislav Petkov
2022-09-21 10:39 ` K Prateek Nayak
2022-09-21 13:10 ` Borislav Petkov
2022-09-21 14:15 ` Dave Hansen
2022-09-21 19:51 ` Borislav Petkov
2022-09-21 19:55 ` Limonciello, Mario
2022-09-22 3:58 ` Ananth Narayan [this message]
2022-09-22 5:44 ` K Prateek Nayak
[not found] ` <20220923160106.9297-1-ermorton@ericmoronsm1mbp.amd.com>
2022-09-23 16:15 ` Ananth Narayan
2022-09-21 15:00 ` Peter Zijlstra
2022-09-21 19:48 ` Borislav Petkov
2022-09-22 8:17 ` Peter Zijlstra
2022-09-22 15:21 ` Rafael J. Wysocki
2022-09-22 15:36 ` Borislav Petkov
2022-09-22 15:53 ` Rafael J. Wysocki
2022-09-22 16:36 ` Dave Hansen
2022-09-22 16:44 ` Dave Hansen
2022-09-22 16:54 ` K Prateek Nayak
2022-09-22 17:01 ` Dave Hansen
2022-09-22 17:48 ` Limonciello, Mario
2022-09-22 18:17 ` Dave Hansen
2022-09-22 18:28 ` Limonciello, Mario
2022-09-23 11:47 ` Ananth Narayan
2022-09-22 19:42 ` Andreas Mohr
2022-09-22 20:10 ` Andreas Mohr
2022-09-22 21:21 ` Dave Hansen
2022-09-22 21:38 ` Limonciello, Mario
2022-09-23 7:42 ` Peter Zijlstra
2022-09-23 7:57 ` Peter Zijlstra
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