Greetings, Confirmed on Intel Clearwater (e7500 chipset w/ RTC built in to NatSemi superio).
G'day, sjames On Tue, 10 Dec 2002, Kevin Hester wrote: > Hi, > > Re: proof that this feature is in the mc146818 > > Sure, I agree - proof good. Saddly, the only datasheets I can find on the > net are for newer clones on this chip. The common dallas semi part datasheet > doesn't show the register usage (arrgh!). However, this via clone does show > register usage (attached). > > For REGISTERA it says that DV0-DV2 must have the value of 010 to turn on the > oscillator. The default value of these bits are zero and the award BIOS on > my board will init these bits correctly if found to be zero. > > The problem occurs in the linux hwclock tool. In rtc.c it spins waiting for > the second count to change. If the RTC has not had the oscillator enabled, > the second count does not change. > > For the patches I've submitted, I've simply called rtc_init(0) from the > vt8601 southbridge init. I didn't want to change other systems right now. > > Ron mentioned he had seen this exact behavior on some 440bx(?) board he was > working on. If someone is out there with some different chip set, you can do > an experiment: > > * Shut the system down > * Remove the battery > * Wait a good long time > * Insert the battery > * Boot linuxbios & linux. If hwclock hangs, then you have this problem. > > Kevin > > > On Tuesday 10 December 2002 18:11, Eric W. Biederman wrote: > > Kevin Hester <[EMAIL PROTECTED]> writes: > > > Hi all, > > > > > > First I'd like to describe a problem I've encountered: > > > > > > I have a virgin motherboard that has never been powered up before. i.e. > > > this board was not manufactured elsewhere and a 'standard' BIOS has never > > > been used on it. > > > > > > When booting this board I discovered an interesting problem: the boot > > > would hang when the "hwclock" tool was invoked by /etc/rcS.d/<some script > > > that reads the rtc>. > > > > > > The underlying problem is that this common linux utility is reading the > > > RTC via the standard IO ports 70-71. Within this RTC window all of the > > > dallas semiconductor RTC clones use a few bits in register 0x0a to enable > > > the clock when power is down. The default values of these bits do not > > > enable the clock - presumably to avoid draining the battery until the > > > boards are first placed into production. > > > > > > I've modified my version of linuxbios to ensure that these bits are set > > > to enable the RTC updates. My question is, where is the best place to > > > make this change? > > > > Assuming your RTC hardware is in your southbridge: > > src/southbridge/<manufacturer>/<chipset>/rtc.c or something like that. > > > > It is my experience that only for reading the real time clock is > > a real time clock a real time clock. The control functions which are > > handled rarely tend to be specific to an individual implementation. Though > > there are generally similarities within a family of implementations. > > > > > 1) In some non linuxbios component (i.e. some little app run at boot > > > time) > > > > > > 2) In linuxbios, but restricted to my mainboard. > > > > > > 3) In linuxbios, but in 'common' code that applies to all intel boards. > > > > In linuxbios common code that applies to your southbridge. > > For now it will probably work best to have that code called from your > > mainboard, and others who need it can call that code as well.\ > > > > > I'm in favor of option 3, but I thought I'd ask first. I think this > > > problem would apply to any board. The reason we haven't seen it before > > > is that most folks are running linux bios on boards that once had a > > > standard bios. The standard bios has already 'activated' the RTC > > > updates. > > > > I suspect being the second BIOS on the boards has certainly had something > > to do with it. But given how much chips vary this may simply be an oddity > > of your particular variation of the board. > > > > > What do you think? > > > > Until I see proof that this feature was in the original motorola mc146818 > > real time clock, and has been in all implementations there after, I > > don't want the code to apply all boards indescrimanently. > > > > Eric > -- -------------------------steven james, director of research, linux labs ... ........ ..... .... 230 peachtree st nw ste 701 the original linux labs atlanta.ga.us 30303 -since 1995 http://www.linuxlabs.com office 404.577.7747 fax 404.577.7743 ----------------------------------------------------------------------- _______________________________________________ Linuxbios mailing list [EMAIL PROTECTED] http://www.clustermatic.org/mailman/listinfo/linuxbios