linux-kernel - Re: [PATCH 0/5] Add P state driver for Intel Core Processors

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: <1732008.aLNltyhYYo@vostro.rjw.lan>
Date:	Thu, 14 Feb 2013 18:36:13 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Dirk Brandewie <dirk.brandewie@...il.com>
Cc:	Viresh Kumar <viresh.kumar@...aro.org>,
	Dave Jones <davej@...hat.com>, linux-kernel@...r.kernel.org,
	cpufreq@...r.kernel.org
Subject: Re: [PATCH 0/5] Add P state driver for Intel Core Processors

On Thursday, February 14, 2013 07:34:56 AM Dirk Brandewie wrote:
> On 02/14/2013 04:21 AM, Rafael J. Wysocki wrote:
> > On Thursday, February 14, 2013 09:38:21 AM Viresh Kumar wrote:
> >> On Wed, Feb 13, 2013 at 10:08 PM, Dirk Brandewie
> >> <dirk.brandewie@...il.com> wrote:
> >>> For the case where both are built-in the load order works my driver uses
> >>> device_initcall() and acpi_cpufreq uses late_initcall().
> >>>
> >>> For the case where both are a module (which I was sure I tested) you are
> >>> right
> >>> I will have to do something.
> >>>
> >>> For now I propose to make my driver built-in only while I sort out the right
> >>> solution for the module build.  Does this seem reasonable to everyone?
> >>
> >> Of-course i am missing something here. Why would anybody want to insert
> >> acpi-cpufreq module when the system supports the pstate driver.
> >>
> >> In case they are mutually exclusive, then we can have something like
> >> depends on !ACPI-DRIVER in the kconfig option of pstate driver.
> >
> > Yes.  Or the other way around (i.e. make acpi_cpufreq depend on
> > !X86_INTEL_PSTATE).
> >
> 
> The issue is that acpi-cpufreq still needs to be available for Intel processors 
> before SandyBridge and for other x86 compatible processors we can't make
> intel_pstate and acpi-cpufreq mutually exclusive.

Right, I forgot about that and recalled it just a minute after sending that
message.
 
> Having intel_pstate built-in solves the issue without the need to patch
> acpi-cpufreq.  I believe that most distros build the scaling drivers in
> so the distro/user will make the explicit decision to use intel_pstate.

But then we need to allow the user to choose acpi_cpufreq anyway if it's
preferred whatever the reason.

Thanks,
Rafael


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
--
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/