linux-kernel - Re: [PATCH v3 6/6] ACPI: import watchdog info of GTDT into platform device

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAJ5Y-eZBvf=pvVTmaPi8PfD1Q5RJeW9uKR-z_DgZRyKc0HfDBw@mail.gmail.com>
Date:	Tue, 26 May 2015 11:35:04 -0400
From:	Ashwin Chaugule <ashwin.chaugule@...aro.org>
To:	Will Deacon <will.deacon@....com>
Cc:	"fu.wei@...aro.org" <fu.wei@...aro.org>,
	"suravee.suthikulpanit@....com" <suravee.suthikulpanit@....com>,
	"linaro-acpi@...ts.linaro.org" <linaro-acpi@...ts.linaro.org>,
	"linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	"tekkamanninja@...il.com" <tekkamanninja@...il.com>,
	"graeme.gregory@...aro.org" <graeme.gregory@...aro.org>,
	"al.stone@...aro.org" <al.stone@...aro.org>,
	"hanjun.guo@...aro.org" <hanjun.guo@...aro.org>,
	"timur@...eaurora.org" <timur@...eaurora.org>,
	"arnd@...db.de" <arnd@...db.de>,
	"linux@...ck-us.net" <linux@...ck-us.net>,
	"vgandhi@...eaurora.org" <vgandhi@...eaurora.org>,
	"wim@...ana.be" <wim@...ana.be>, "jcm@...hat.com" <jcm@...hat.com>,
	"leo.duran@....com" <leo.duran@....com>,
	"corbet@....net" <corbet@....net>,
	Mark Rutland <Mark.Rutland@....com>,
	Catalin Marinas <Catalin.Marinas@....com>
Subject: Re: [PATCH v3 6/6] ACPI: import watchdog info of GTDT into platform device

On 26 May 2015 at 11:18, Will Deacon <will.deacon@....com> wrote:
> On Tue, May 26, 2015 at 04:02:56PM +0100, Ashwin Chaugule wrote:
>> On 26 May 2015 at 08:28, Will Deacon <will.deacon@....com> wrote:
>> > On Mon, May 25, 2015 at 11:03:13AM +0100, fu.wei@...aro.org wrote:
>> >> From: Fu Wei <fu.wei@...aro.org>
>> >>
>> >> Parse SBSA Generic Watchdog Structure in GTDT table of ACPI,
>> >> and create a platform device with that information.
>> >> This platform device can be used by the ARM SBSA Generic
>> >> Watchdog driver.
>> >>
>> >> Tested-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>
>> >> Tested-by: Timur Tabi <timur@...eaurora.org>
>> >> Signed-off-by: Fu Wei <fu.wei@...aro.org>
>> >> ---
>> >>  arch/arm64/kernel/acpi.c | 145 +++++++++++++++++++++++++++++++++++++++++++++++
>> >>  1 file changed, 145 insertions(+)
>> >
>> > Why does this all need to be under arch/arm64? The GTDT really isn't
>> > architecture-specific, so I'd *much* rather it was parsed in the driver code
>> > itself, like we already do for the architected timer. The GIC is an
>> > exception because it's in the MADT, which we need to parse in the arch code
>> > to configure SMP properly.
>>
>> I'm not really against refactoring the code. But the GTDT looks quite
>> specific to ARM..
>>
>> ---8<----
>> 5.2.24 Generic Timer Description Table (GTDT)
>> This section describes the format of the Generic Timer Description
>> Table (GTDT), which provides
>> OSPM with information about a system’s Generic Timers configuration.
>> The Generic Timer (GT) is
>> a standard timer interface implemented on ARM processor-based systems.
>> The GT hardware
>> specification can be found at Links to ACPI-Related Documents
>> (http://uefi.org/acpi) under the
>> heading ARM Architecture. The GTDT provides OSPM with information
>> about a system's GT
>> interrupt configurations, for both per-processor timers, and platform
>> (memory-mapped) timers.
>> The GT specification defines the following per-processor timers:
>> • Secure privilege level 1 (EL1) timer,
>> • Non-Secure EL1 timer,
>> • Non-Secure privilege level 2 (EL2) timer,
>> • Virtual timer,
>> and the following Platform (memory-mapped) timers.
>> • GT Block
>> • Server Base System Architecture (SBSA) Generic Watchdog
>> ---8<----
>
> Sure, the device it describes may only ever exist on ARM systems, but by
> that logic then we should be moving lots of drivers back under arch/arm[64].

Sure. Not arguing about that. :) You said the GTDT isn't really arch
specific. That was a bit confusing.

>
> The ARM architecture says precisely *nothing* about ACPI, so we should
> try to keep arch/arm64/kernel/acpi.c to a minimum and not shovel all sorts
> of table conversion code in there for random peripherals.
>
> Will
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/