Patch to detect 8254 timer munging in BIOS calls (needs testing)

[Andreas Hauser]

dillon wrote @ Fri, 19 Nov 2004 14:00:51 -0800 (PST):

>     The question is: (a) does this work (detect the access and print the
>     warning) and (b) prevent runaway clocks.

Seems to work, but the correction seems to be one hour off.
Without the patch my clock was pretty exactly running at twice the expected
speed (especially noticable when i benchmarked some of my programms and got
double of the expected times), now it runs aligned with the wall clock and
the benchmarks are back to what was expected.

This happened within 20 minutes and demonstrates the one hour off problem:

----8<---- messages ----8<----
Nov 20 18:08:28 tower sudo:       ah : TTY=ttyv0 ; PWD=/usr/home/ah ; USER=root ; COMMAND=/bin/date 1709
Nov 20 17:09:00 tower date: date set by ah
Nov 20 18:11:15 tower kernel: Warning: BIOS messed around with the 8254, resetting it
Nov 20 18:11:15 tower kernel: Warning: BIOS messed around with the 8254, resetting it
Nov 20 19:15:32 tower kernel: Warning: BIOS messed around with the 8254, resetting it
Nov 20 19:15:32 tower kernel: Warning: BIOS messed around with the 8254, resetting it
Nov 20 19:23:08 tower sudo:       ah : TTY=ttyp9 ; PWD=/usr/home/ah ; USER=root ; COMMAND=/usr/bin/su -
Nov 20 17:23:00 tower date: date set by ah
---->8---- messages ---->8----


Andy