[vdr] Re: NVRAM WakeUp

[Sergei Haller <Sergei.Haller@math.uni-giessen.de>]

On Fri, 19 Oct 2001, Patrick GUENEAU wrote:

> Hello,
>
> One thing very important is that even if the nvram is altered and the
> wakeup scheduled, nothing tells the bios to read this configuration and
> do program the RTC.
>
> That the reason why Sergi mentionned that you should reboot once the
> BIOS reads the new nvram config and program the RTC.

In fact, it seems, that mainboards with Award v6.0 BIOS do not have this
problem. you just set the time with nvram-wakeup, shut down your computer
and it will wake up at the right time.

> I tried many things without any success until Sergi annonced his first
> release and i have read his comments.
>
> Maybe there is something like a bios call to enforce reading nvram ;

if someone could tell us how to make such a call ...

> it
> seems very strange too that hwclock is able to change the clock without
> having to do anything else than writing to nvram.
>
> As the addresses used by hwclock are below the first bytes you can dump
> from /dev/nvram, it seems there are other addresses in nvram.
> i found that addresses between clock addresses (i.e. bytes 0,2,4 are for
> HWCLOCK and 1,3 and 5 for ALARM) should be the right ones to directly
> change the wakeup time. I tested a modified hwclock program to dump
> alarm time instead of hardware clock and it worked.

could you send me your program please?

meanwhile I tried to set the ALARM via ioctl(RTC_ALM_SET) additionally to
the method in nvram-wakeup. No success. (at least not with my MSI MS-6351)

> On Thu, 18 Oct 2001, Arno Esser wrote:
>
> > Based on your hint I tried the real time clock functionality in
> > kernel (see linux/Documentation/rtc.txt ). The test programs run
> > very fine, but it had no effect on the real time clock alarm
> > settings. In more detail: the alarm clock work if I set my
> > computer to suspend mode. There is no effect, if I power off my
> > machine. But I thought that would be possible with the small nvram
> > utility.

as Patrick said, there must be some bios call, which enforces reading of
nvram. (which is done on shutdown on some bioses and only at boot time on
other)

The question is: what is done on this call?

One of the thoughts was: maybe BIOS sets the rtc alarm (which dont have a
date) to the time of the wakeup, so the alarm is triggered every 24h, then
BIOS compares the date of the clock with the date of the wakeup and power
on the computer if they are equal.
(But I had no luck with that)

> > So my question is can I enhance the rtc functionality to alter the
> > values in bios or do I really have to spent hours changing the bios
> > settings and investigating this terrible bios hexdump? Any hints on
> > that?

Unfortunately every BIOS (or even every MB) stores their values at
different adresses.

c ya
        Sergei

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