Re: apm-bios and rtc

Garst R. Reese (
Mon, 02 Mar 1998 23:40:02 -0400

C. Scott Ananian wrote:
> On Sun, 1 Mar 1998 "Garst R. Reese" <> wrote:
> > I finally got apm_bios to blank my screen with no error msgs.
> > In apm_bios.c, I set APM_SET_DISPLAY_POWER_STATE "b" to 0x0100 instead
> > of 0x01ff.
> [...]
> > After many printk's I disabled rtc support in the kernel. That did the
> > trick.
> [...]
> Could you confirm that 0x01FF *doesn't* work, even if rtc support is
> turned off?
YES, confirmed. But, I also discovered an interaction with the blank
time set with setterm -blank and the blank time set in my bios. During
testing it set the bios to 1 min. Setterm was set to 15 min., which was
longer than I sat around staring at a blank screen. I then set the bios
to 8 min. and checked on it periodically, only to discover that setterm
would unblank the bios blank. I am trying setterm -blank 60 now. The
machine should suspend before that happens, but I don't think suspend
works if I have X on another VC. Now I am not certain if it was
disabling rtc or setting the bios blank time to 1 that made things
appear to work :( Testing screen blanking is sorta boring :)

> [i'm currently compiling a 'minimal' kernel to see if I can track down
> some other apm anomalies]
> > APM bios V1.0 (Driver version 1.3), linux 2.1.88, PCMCIA-cs v3.0.0
> > MidWestMicro Elite Soundbook DX2/66
> What BIOS is your laptop using (should be displayed in a message at boot;
> my laptop reads 'Phoenix BIOS 4.05')?
System Soft V1.0 (2208-05)

> > I also noticed in console.c that apm screen blanking is called if
> > CONFIG_APM is set. Shouldn't this be ifdef CONFIG_APM_DISPLAY_BLANK ?
> No, see drivers/char/apm_bios.c, function apm_display_blank.
> All APM-related options are restricted to the apm_bios.c file so that the
> #defines at the top of apm_bios.c work as you would expect them to.
I did look at that code. I just did not see the point of even calling
apm_display_blank if CONFIG_APM_DISPLAY_BLANK is not set, which is
should not be if CONFIG_APM is not set. No big deal, the effect is the
> --Scott
> @ @
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-oOO-(_)-OOo-=-=-=-=-=
> C. Scott Ananian: / Declare the Truth boldly and
> Laboratory for Computer Science/Crypto / without hindrance.
> Massachusetts Institute of Technology /META-PARRESIAS AKOLUTOS:Acts 28:31
> -.-. .-.. .. ..-. ..-. --- .-. -.. ... -.-. --- - - .- -. .- -. .. .- -.
> PGP key available via finger and from


- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to