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From: Grant Likely <grant.likely@linaro.org>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: "hanjun.guo@linaro.org" <hanjun.guo@linaro.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Mark Rutland <Mark.Rutland@arm.com>,
	Olof Johansson <olof@lixom.net>,
	"graeme.gregory@linaro.org" <graeme.gregory@linaro.org>,
	Arnd Bergmann <arnd@arndb.de>,
	Sudeep Holla <Sudeep.Holla@arm.com>,
	Will Deacon <Will.Deacon@arm.com>,
	Jason Cooper <jason@lakedaemon.net>,
	Marc Zyngier <Marc.Zyngier@arm.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	Mark Brown <broonie@kernel.org>, Rob Herring <robh@kernel.org>,
	Robert Richter <rric@kernel.org>, Lv Zheng <lv.zheng@intel.com>,
	Robert Moore <robert.moore@intel.com>,
	Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>,
	Liviu Dudau <Liviu.Dudau@arm.com>,
	Randy Dunlap <rdunlap@infradead.org>,
	Charles Garcia-Tobin <Charles.Garcia-Tobin@arm.com>,
	"linux-acpi@vger.kernel.org" <linux-acpi@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linaro-acpi@lists.linaro.org" <linaro-acpi@lists.linaro.org>
Subject: Re: [PATCH v3 00/17] Introduce ACPI for ARM64 based on ACPI 5.1
Date: Sun, 14 Sep 2014 21:31:16 -0700	[thread overview]
Message-ID: <20140915043116.9985CC407E8@trevor.secretlab.ca> (raw)
In-Reply-To: <20140911153739.GA24416@localhost>

On Thu, 11 Sep 2014 16:37:39 +0100, Catalin Marinas <catalin.marinas@arm.com> wrote:
> On Thu, Sep 11, 2014 at 02:29:34PM +0100, Grant Likely wrote:
> > Regarding the requests to refactor ACPICA to work better for ARM. I
> > completely agree that it should be done, but I do not think it should be
> > a prerequisite to getting this core support merged. That kind of
> > refactoring is far easier to justify when it has immediate improvement
> > on the mainline codebase, and it gives us a working baseline to test
> > against. Doing it the other way around just makes things harder.
> 
> I have to disagree here. As I said, I'm perfectly fine with refactoring
> happening later but I'm not happy with compiling in code with undefined
> behaviour on ARM that may actually be executed at run-time.
> 
> I'm being told one of the main advantages of ACPI is forward
> compatibility: running older kernels on newer hardware (potentially with
> newer ACPI version tables). ACPI 5.1 includes partial support for ARM
> but the S and C states are not defined yet. We therefore assume that
> hardware vendors deploying servers using ACPI would not provide such
> yet to be defined information in ACPI 5.1 tables.

We're good on this front. ACPI-future platforms aren't allowed to use
new features when booting an older kernel. ACPI has a mechanism to check
version numbers. Similarly, when ACPI-future defines those states, the
kernel shouldn't expose them to an older platform.

> What if in a year time we get ACPI 5.2 or 6 (or an errata update)
> covering the S and C states for ARM? I would expect hardware vendors
> to take advantage and provide such information in ACPI tables. Can we
> guarantee that a kernel with the current ACPI patches wouldn't blow up
> when it tries to interpret the new tables?

Yes - at least as much as we can guarantee anything in systems
programming.

g.

  parent reply	other threads:[~2014-09-15  4:31 UTC|newest]

Thread overview: 117+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-01 14:57 [PATCH v3 00/17] Introduce ACPI for ARM64 based on ACPI 5.1 Hanjun Guo
2014-09-01 14:57 ` [PATCH v3 01/17] ARM64: Move the init of cpu_logical_map(0) before unflatten_device_tree() Hanjun Guo
2014-09-01 14:57 ` [PATCH v3 02/17] ARM64 / ACPI: Get RSDP and ACPI boot-time tables Hanjun Guo
2014-09-09 16:26   ` Catalin Marinas
2014-09-09 16:41     ` Jon Masters
2014-09-09 16:44       ` Jon Masters
2014-09-09 17:15       ` Mark Rutland
2014-09-09 17:33         ` Jon Masters
2014-09-09 17:50         ` Lorenzo Pieralisi
2014-09-09 18:05           ` Sudeep Holla
2014-09-09 19:06             ` Jon Masters
2014-09-10 11:13               ` Hanjun Guo
2014-09-10 12:33                 ` Catalin Marinas
2014-09-10 21:51                   ` Grant Likely
2014-09-11 11:01                     ` Catalin Marinas
2014-09-14 15:40                       ` Grant Likely
2014-09-14 21:59                         ` Catalin Marinas
2014-09-15  3:53                           ` Grant Likely
2014-09-16  5:29                     ` Zheng, Lv
2014-09-10 21:41                 ` Grant Likely
2014-09-09 16:54     ` Mark Rutland
2014-09-10  7:30     ` Hanjun Guo
2014-09-10 21:37     ` Grant Likely
2014-09-01 14:57 ` [PATCH v3 03/17] ARM64 / ACPI: Introduce lowlevel suspend function Hanjun Guo
2014-09-09 16:35   ` Catalin Marinas
2014-09-09 22:04     ` Graeme Gregory
2014-09-01 14:57 ` [PATCH v3 04/17] ARM64 / ACPI: Introduce early_param for "acpi" Hanjun Guo
2014-09-09 16:37   ` Catalin Marinas
2014-09-09 17:17   ` Bjorn Helgaas
2014-09-09 22:14     ` Jon Masters
2014-09-10 13:04       ` Will Deacon
2014-09-10 13:21         ` Bjorn Helgaas
2014-09-10 18:30           ` Will Deacon
2014-09-10 21:58           ` Grant Likely
2014-09-01 14:57 ` [PATCH v3 05/17] ARM64 / ACPI: If we chose to boot from acpi then disable FDT Hanjun Guo
2014-09-01 14:57 ` [PATCH v3 06/17] ARM64 / ACPI: Make PCI optional for ACPI on ARM64 Hanjun Guo
2014-09-01 14:57 ` [PATCH v3 07/17] ARM64 / ACPI: Parse FADT table to get PSCI flags for PSCI init Hanjun Guo
2014-09-01 14:57 ` [PATCH v3 08/17] ACPI / table: Print GIC information when MADT is parsed Hanjun Guo
2014-09-01 14:57 ` [PATCH v3 09/17] ARM64 / ACPI: Parse MADT for SMP initialization Hanjun Guo
2014-09-03 17:21   ` Lorenzo Pieralisi
2014-09-04 15:29     ` Hanjun Guo
2014-09-09  4:29       ` Jon Masters
2014-09-09  5:11         ` Hanjun Guo
2014-09-09  5:34           ` Jon Masters
2014-09-09 16:52       ` Lorenzo Pieralisi
2014-09-09 17:00         ` Jon Masters
2014-09-09 17:02         ` Jon Masters
2014-09-09  4:23   ` Jon Masters
2014-09-09  4:57     ` Hanjun Guo
2014-09-09  5:44       ` Jon Masters
2014-09-09 16:00         ` Hanjun Guo
2014-09-09 16:04           ` Jon Masters
2014-09-09 16:14             ` Hanjun Guo
2014-09-11 14:15             ` Will Deacon
2014-09-12 21:30               ` Jon Masters
2014-09-11 10:24   ` Grant Likely
2014-09-01 14:57 ` [PATCH v3 10/17] ACPI / processor: Make it possible to get CPU hardware ID via GICC Hanjun Guo
2014-09-03 16:27   ` Lorenzo Pieralisi
2014-09-08 13:10     ` Hanjun Guo
2014-09-01 14:57 ` [PATCH v3 11/17] ARM64 / ACPI: Introduce ACPI_IRQ_MODEL_GIC and register device's gsi Hanjun Guo
2014-09-11 11:08   ` Grant Likely
2014-09-11 11:34     ` Grant Likely
2014-09-12  9:42     ` Hanjun Guo
2014-09-01 14:57 ` [PATCH v3 12/17] ACPI / table: Add new function to get table entries Hanjun Guo
2014-09-01 14:57 ` [PATCH v3 13/17] ARM64 / ACPI: Add GICv2 specific ACPI boot support Hanjun Guo
2014-09-01 17:35   ` Marc Zyngier
2014-09-02  8:28     ` [Linaro-acpi] " Alexander Spyridakis
2014-09-02 11:48     ` Tomasz Nowicki
2014-09-02 13:02       ` Marc Zyngier
2014-09-02 15:45         ` Hanjun Guo
2014-09-02 15:59           ` Marc Zyngier
2014-09-02 16:11           ` Sudeep Holla
2014-09-03 10:30           ` Marc Zyngier
2014-09-03 11:17             ` Hanjun Guo
2014-09-04 14:03               ` Hanjun Guo
2014-09-09  6:21             ` Jon Masters
2014-09-03  9:26         ` Tomasz Nowicki
2014-09-03 14:57           ` Arnd Bergmann
2014-09-05  8:52             ` Tomasz Nowicki
2014-09-05  9:47             ` Marc Zyngier
2014-09-05 10:13               ` [Linaro-acpi] " Arnd Bergmann
2014-09-05 10:36                 ` Tomasz Nowicki
2014-09-05 10:39                 ` Marc Zyngier
2014-09-05 10:49                   ` Tomasz Nowicki
2014-09-09  6:27             ` Jon Masters
2014-09-11 13:43         ` Grant Likely
2014-09-02 16:34       ` Catalin Marinas
2014-09-11 11:48       ` Grant Likely
2014-09-11 12:01         ` Marc Zyngier
2014-09-09  6:14     ` Jon Masters
2014-09-03 18:42   ` Arnd Bergmann
2014-09-04 10:10     ` Tomasz Nowicki
2014-09-04 10:14       ` Arnd Bergmann
2014-09-04 10:39         ` Tomasz Nowicki
2014-09-09  6:35     ` Jon Masters
2014-09-01 14:57 ` [PATCH v3 14/17] ARM64 / ACPI: Parse GTDT to initialize arch timer Hanjun Guo
2014-09-01 14:57 ` [PATCH v3 15/17] ARM64 / ACPI: Select ACPI_REDUCED_HARDWARE_ONLY if ACPI is enabled on ARM64 Hanjun Guo
2014-09-01 14:57 ` [PATCH v3 16/17] ARM64 / ACPI: Enable ARM64 in Kconfig Hanjun Guo
2014-09-11 15:18   ` Lorenzo Pieralisi
2014-09-01 14:57 ` [PATCH v3 17/17] Documentation: ACPI for ARM64 Hanjun Guo
2014-09-11 13:29 ` [PATCH v3 00/17] Introduce ACPI for ARM64 based on ACPI 5.1 Grant Likely
2014-09-11 13:49   ` Will Deacon
2014-09-12 21:38     ` Jon Masters
2014-09-12 21:43       ` Jon Masters
2014-09-15  4:21     ` Grant Likely
2014-09-11 14:23   ` Rafael J. Wysocki
2014-09-11 14:04     ` Grant Likely
2014-09-11 15:37   ` Catalin Marinas
2014-09-11 15:57     ` Sudeep Holla
2014-09-11 16:06       ` Graeme Gregory
2014-09-11 16:14         ` Sudeep Holla
2014-09-15  4:31     ` Grant Likely [this message]
2014-09-15  9:15       ` Catalin Marinas
2014-09-15 22:48         ` Grant Likely
2014-09-16 10:12           ` Catalin Marinas
2014-09-11 16:05   ` Olof Johansson
2014-09-15  4:37     ` Grant Likely

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