[#4404] default kernel config selects GENERIC_TIME
Submitted By: Graf Yang
Open Date
2008-09-02 23:46:38 Close Date
2009-09-22 00:02:07
Priority:
Low Assignee:
Graf Yang
Status:
Closed Fixed In Release:
N/A
Found In Release:
2008R1.5-RC3 Release:
Category:
Kernel Functions Board:
N/A
Processor:
ALL Silicon Revision:
Is this bug repeatable?:
Yes Resolution:
Fixed
Uboot version or rev.:
Toolchain version or rev.:
any
App binary format:
N/A
Summary: default kernel config selects GENERIC_TIME
Details:
If GENERIC_TIME is selected, the time related system call only get coarse time that based on tick. 2008R1 disabled it on every board.
Follow-ups
--- Graf Yang 2008-09-03 00:30:35
NO_HZ depends on this option, so could not blindly close it.
--- Robin Getz 2009-01-08 15:09:53
If I understand the description (which I will re-word since I don't understand
the existing description)
When GENERIC_TIME is selected (which it is by default for all the ADI boards)
then all time keeping in the kernel has a resolution based on the default clock
source - since we also have GENERIC_CLOCKEVENTS selected - the clock source used
is jiffies -- giving all timing keeping in the kernel a jiffy based resolution.
This is as designed - and is working properly -- no bug.
To change this behavior:
a) select CYCLES_CLOCKSOURCE (Which we do not do by default since
CYCLES/CYCLES2 is writable in userspace)
b) create a new platform driver for clock source/clock event which
uses gptimers as a clock source/event
I think b) would be a good idea, but it still not a bug.
-Robin
--- Graf Yang 2009-01-09 01:27:15
What I need to do is to create a platform driver for clock source/clock event
which uses core-timer or gptimers. Then user can get more precise time through
sys_gettimeofday().
SMP kernel on BF561 will not boot with this option. (Currently, If SMP is
selected, GENERIC_TIMER will be deselected.) I will make it work when
SMP+GENERIC_TIMER.
--- Mike Frysinger 2009-01-09 01:45:31
writing a gptimer clocksource platform driver would also be good because we
could enable it by default and always enable GENERIC_TIME/GENERIC_CLOCKEVENTS
(and delete arch/blackfin/kernel/time.c)
--- Robin Getz 2009-01-09 10:19:18
Yeah, having an option for:
- core timer (CLK domain)
- general purpose timers (SCLK domain)
would be great.
--- Graf Yang 2009-05-20 04:38:02
Now both the core timer and gptimer0 can generate ticks.
Both the cycles and gptimer0 can be the clock source.
--- Graf Yang 2009-09-22 00:02:07
It has been fixed long time ago, so close it.
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