On Tuesday 14 February 2006 18:44, Thomas Renninger wrote: > Pavel Machek wrote: > > On Pá 10-02-06 09:06:43, Stefan Seyfried wrote: > >> On Wed, Feb 08, 2006 at 12:57:53PM +0000, Matthew Garrett wrote: > >>> The included patch adds support for power management methods to register > >>> callbacks in order to allow drivers to check if the system is on AC or > >>> not. Following patches add support to ACPI and APM. Feedback welcome. > >> Ok. Maybe i am not seeing the point. But why do we need this in the kernel? > >> Can't we handles this easily in userspace? > > > > Some kernel parts need to now: for example powernow-k8: some > > frequencies are not allowed when you are running off battery. [Just > > now it is solved by not allowing those frequencies at all unless ACPI > > is available; quite an ugly solution.] > > > Allowed CPUfreqs are exported via _PPC. > This is why a lot hardware sends an ac_adapter and a processor event > when (un)plugging ac adapter. > Limiting cpufreq already works nice that way. > > AMD64 laptops are booting with lower freqs per default until they are > pushed up, so there shouldn't be anything critical? This is not true as far as my box is concerned (Asus L5D). It starts with the _highest_ clock available. > For the brightness part, I don't see any "laptop is going to explode" > issue. > I always hated the brightness going down when I unplugged ac on M$ Currently I have the same problem on Linux, but I don't know the solution (yet). Any hints? :-) Rafael
