Bug 7242

argh, not this again.

Please include the full `dmesg' output.

Please clarify the "Most recent kernel where this bug did not occur".  You say
2.17.13, but there's no such kernel version.

Created attachment 9144 [details]
dmesg output 2.6.17.13

Created attachment 9145 [details]
dmesg output 2.6.18

there are some errors at the end like:
<4>TSC appears to be running slowly. Marking it as unstable
<6>Time: scx200_hrt clocksource has been installed.

> You say 2.17.13, but there's no such kernel version.
Damn... I'll never write kernel-versions by hand... I'll do a copy&paste job 
next time!
Well, i meant 2.6.17.13 of cause - sorry for that.

Hmmmm. I'll ping Jim Cromie (he wrote the scx200_hrt code) and see if he has a
clue if it is safe for this hardware.

Alexander: Does booting w/ clock=tsc work around this issue?

Alex: pls add 'mhz27=1' to your modprobe and report.  Ive had 1 other report
where this apparently fixed things.  Also, please supply your
/sys/devices/system/clocksource/clocksource0/* values, and confirm effects of
using clock=tsc on bootline, and of the modprobing.

Others, pls comment: May be an off-by-1 err in request_region's size (5, should
be 6).  5 excludes TMCNFG reg, which has mhz27 flag.  Would writing 1 byte past
the region manifest an err message, be silently ignored, or silently succeed ??

>Alexander: Does booting w/ clock=tsc work around this issue?
Actually not and it looks like it's about 20 times slower than normal (seconds 
on date output don't change).

With that kernel option enabled:
?> cat /sys/devices/system/clocksource/clocksource0/available_clocksource 
scx200_hrt jiffies tsc pit 

?> cat /sys/devices/system/clocksource/clocksource0/current_clocksource 
tsc 

I added 'clock=scx200_hrt scx200_hrt.mhz27=1' to my kernel and now things look 
good for me.

?> cat /sys/devices/system/clocksource/clocksource0/current_clocksource
scx200_hrt 

BTW some interesting dmesg lines with my current setup ( clock=scx200_hrt 
scx200_hrt.mhz27=1 )

<6>enabling scx200 high-res timer (27 MHz +0 ppm)
...
<6>Time: scx200_hrt clocksource has been installed.
...
<4>TSC appears to be running slowly. Marking it as unstable

hi Alex,  Those 3 lines you quoted (entry #8) are expected.  But in #7 you
showed tsc being used.  That implies that #7 did not detect 'running slowly',
hence tsc was preferred.  Had it been detected, you would have fallen back to
either scx200_hrt, or finally PIT.  Is the detection somewhat unreliable on your
box ?

>But in #7 you showed tsc being used.
>That implies that #7 did not detect 'running slowly',hence tsc was preferred.
I used clock=tsc at boot-time in #7 as suggested.

>Had it been detected, you would have fallen back to either scx200_hrt, or 
finally PIT.
>Is the detection somewhat unreliable on your box ?
Well, I'm not quite sure how the kernel should behave but when 
using 'clock=tsc', tsc seems to be forced.
Even though I'm getting '<4>TSC appears to be running slowly. Marking it as 
unstable'.

?> cat /sys/devices/system/clocksource/clocksource0/current_clocksource 
tsc 

Normaly it uses scx200_hrt and does not detect errors in that module.

Jim, i got you mail some hours ago and i've tested you patch right now.

I'm booting without any clock-related kernel parameters and things are looking 
quite nice atm.

Thanks a lot ;-)

This should be fixed w/ the current -git. Please reopen if that's not the case.