From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 17 Dec 2003 10:51:39 +0100 To: Benjamin Herrenschmidt Cc: Lee Braiden , Sven Luther , debian-powerpc@lists.debian.org, linuxppc-dev@lists.linuxppc.org Subject: Re: Would setting the CONFIG_RTC option break the powerpc kernel on your machine ? Message-ID: <20031217095139.GC2283@iliana> References: <20031216105656.GA5291@iliana> <1071642293.753.414.camel@gaston> <200312170717.36564.jel@ntlworld.com> <1071646057.6370.482.camel@gaston> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 In-Reply-To: <1071646057.6370.482.camel@gaston> From: Sven Luther Sender: owner-linuxppc-dev@lists.linuxppc.org List-Id: BTW, should this discussion not be moved to linuxppc mailing lists ? On Wed, Dec 17, 2003 at 06:27:37PM +1100, Benjamin Herrenschmidt wrote: > On Wed, 2003-12-17 at 18:17, Lee Braiden wrote: > > On Wednesday 17 Dec 2003 6:24 am, Benjamin Herrenschmidt wrote: > > > CONFIG_RTC will definitely break a pmac > > > > I think I heard something about clock/timer problems on PPC a long time ago, > > but could never track down an issue. Wouldn't it be best to remove RTC on > > PPC or document the problem with a (read help) or something? > > > > Is the PPC RTC (as opposed to GENERIC_RTC) stuff automatically in there, or > > something? Or is it this PPC_RTC that's broken? > > Well... CONFIG_RTC enables the "PC style" RTC driver that taps IO ports > to look for an RTC chip of the kind found in x86 machines. Such a chip > doesn't exist on powermac and this random IO port tapping can actually > crash the machine. And i guess that this PC style RTC is found on the southbridge, right ? Let me check the VIA docs. Yep, it indeed is there, and i doubt that there is another clock on the system. Not sure though. > CONFIG_PPC_RTC/CONFIG_GENERIC_RTC is a different driver that provides > the /dev/rtc interface but relies on hooks provided by the platform > code for actually getting/setting the RTC content. The PowerMac platform > provides hooks for the different kind of RTC chips found on Macs (that > is basically access to the RTC via via-cuda or via-pmu). CHRP or Mmm, these are external via chips on mac hardware used for clocks ? > PReP machines should provide their own hooks, it's possible that what > CHRP provides doesn't work properly on the Pegasos, in which case we'd > have to fix this. Another solution would be to : 1) build a pegasos specific config with CONFIG_RTC, but not the other two. <= Not good, since it would mean over one hour compil more, and one more binary packages. Already like that the ftp-masters are not happy. 2) build all RTC stuff as modules, and let userland choose the one it needs. 3) have CONFIG_RTC check the subarch or something and not work if it recognize hardware it doesn't know about or something. Friendly, Sven Luther ** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/