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: <200902162312.50556.rjw@sisk.pl>
Date:	Mon, 16 Feb 2009 23:12:48 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Arjan van de Ven <arjan@...radead.org>
Cc:	pm list <linux-pm@...ts.linux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Arve Hjønnevåg <arve@...roid.com>,
	Alan Stern <stern@...land.harvard.edu>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Pavel Machek <pavel@....cz>,
	Nigel Cunningham <nigel@...el.suspend2.net>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	mark gross <mgross@...ux.intel.com>,
	"Woodruff, Richard" <r-woodruff2@...com>,
	Uli Luckas <u.luckas@...d.de>,
	Igor Stoppa <igor.stoppa@...ia.com>,
	Brian Swetland <swetland@...gle.com>,
	Len Brown <lenb@...nel.org>
Subject: Re: [RFD] Automatic suspend

On Monday 16 February 2009, Arjan van de Ven wrote:
> On Mon, 16 Feb 2009 22:48:32 +0100
> "Rafael J. Wysocki" <rjw@...k.pl> wrote:
> 
> > > Userland should never ever control the state of a device like this
> > > directly. It should do so by a) closing the device and b) setting
> > > latency / functional requirements.
> > 
> > The user, however, may want to forcibly put a device into a low power
> > state without stopping all of the applications that depend on it (eg.
> > have it open). Do you think that we shouldn't allow users to do such
> > things?
> 
> I would think that that is a bad mistake to do. It basically breaks the 
> contract that the kernel has with userspace.... 

OK, so I think there are two things that user space may be allowed to do as
far as putting devices into low power states is concerned:
* disable/enable the automatic power management of the device (provided that
  the driver supports the automatic PM)
* check what power states devices are in.

Thanks,
Rafael
--
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/

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ