From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wes Felter Subject: Re: voltage tables Date: Tue, 31 Jul 2007 14:56:29 -0500 Message-ID: References: <20070730230439.GB6949@tatooine.rebelbase.local> <200707302241.29635.lenb@kernel.org> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <200707302241.29635.lenb@kernel.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: cpufreq-bounces@lists.linux.org.uk Errors-To: cpufreq-bounces+glkc-cpufreq=gmane.org+glkc-cpufreq=gmane.org@lists.linux.org.uk Content-Type: text/plain; charset="us-ascii"; format="flowed" To: cpufreq@lists.linux.org.uk Len Brown wrote: > On Monday 30 July 2007 19:04, markus reichelt wrote: >> Hi, >> >> just a thought.... with more and more people wondering why cpufreq >> doesn't work on their over/underclocked systems, what about offering >> the possibility to use static (and thus easily tweakable) voltage >> tables instead of/parallel to the ACPI-approach? [snip] > Going forward, I believe that the hardware guys have no plans to > maintain any sort of reasonable compatibility or even straightforward > decoding of the bit pattern that gets written to PERF_CTL -- > so the reason that speedstep-centrino and its hard-coded tables > became deprecated will be even more true in the future. User-provided tables != hard-coded tables. What if acpi-cpufreq dumped the ACPI table in some semi-human-readable format and then allowed the user to tweak it (by guessing, since the hardware is undocumented) and then push the tweaked table back into the driver at runtime? The driver would still not contain any tables and thus the old speedstep-centrino maintenance problem would not exist. There is a patch for speedstep-centrino that adds an op_points_table file in sysfs; it could be ported to acpi-cpufreq. http://gentoo-wiki.com/HOWTO_Undervolt_a_Pentium_M_CPU#Getting_the_current_voltage_settings > Further, I've not played with this, but my understanding is that > on the Extreme parts, the way to over-clock them is to have Most overclockers buy cheap non-extreme parts and set the FSB frequency out of spec; that's why the ACPI tables are wrong. Wes Felter - wesley@felter.org