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SubjectBug in console driver?
Hi!

I suppose there is a bug in the 2.4-kernel console driver
(../drivers/char/console.c).

It seems that (if there is a slow video device) this driver disables the
handling of interrupts while writing or switching the consoles.

Symptoms:

If you use the VESA framebuffer, switching to another console prevents
updating the internal kernel clock (jiffies, xtime) for a short time.
This effect can grow up to some seconds:

Load the GNU Midnight Commander (mc) and synchronize kernel clock and
hardware clock with the command 'hwclock --hctosys'.

Then you can see the the difference with 'hwclock && date'.

# hwclock && date
Sun Sep 16 10:31:33 2001 -0,154753 ...
Sun Sep 10 10:31:32 CEST 2001

Now hold down the keys <Ctrl+o> for a some seconds. (This switches the
window of the Midnight Commander on/off many times)

If you now compare the clocks you yield a difference of some seconds:

# hwclock && date
Sun Sep 16 10:33:17 2001 -0,456384 ...
Sun Sep 16 10:33:12 CEST 2001

5 seconds - I think this is a bug.


My system:

Intel Pentium II, 512 MB RAM
NVIdia Riva TNT2 M64 with 32 MB
Kernel 2.4.4 and 2.4.7
SuSE Linux 7.2
VESA Framebuffer


Greetings

Michael





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