On 06/25/2013 05:01 PM, Rafael J. Wysocki wrote: > On Monday, June 24, 2013 05:25:18 PM Shuah Khan wrote: >> pm_trace uses the system's Real Time Clock (RTC) to save the magic number. >> Reason for this is that the RTC is the only reliably available piece of >> hardware during resume operations where a value can be set that will >> survive a reboot. >> >> Consequence is that after a resume (even if it is successful) your system >> clock will have a value corresponding to the magic number instead of the >> correct date/time! It is therefore advisable to use a program like ntp-date >> or rdate to reset the correct date/time from an external time source when >> using this trace option. >> >> There is no run-time message to warn users of the consequences of enabling >> pm_trace. Adding a warning message to pm_trace_store() will serve as a >> reminder to users to set the system date and time after resume. >> >> Signed-off-by: Shuah Khan <[email protected]> >> --- >> kernel/power/main.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/kernel/power/main.c b/kernel/power/main.c >> index d77663b..fd744d1 100644 >> --- a/kernel/power/main.c >> +++ b/kernel/power/main.c >> @@ -528,6 +528,8 @@ pm_trace_store(struct kobject *kobj, struct >> kobj_attribute *attr, >> >> if (sscanf(buf, "%d", &val) == 1) { >> pm_trace_enabled = !!val; >> + pr_warn("PM: Enabling pm_trace changes system date and time >> after resume.\n"); >> + pr_cont("PM: Remember to set correct time after resume\n"); > > You can do it like this: > > + pr_warn("PM: Enabling pm_trace changes system date and time after > resume.\n" > + "PM: Remember to set correct time after resume\n"); > > No need to use pr_cont(). :-)
:) Yeah. > > And I'd say "during" instead of "after" in the first sentence. > > I'd also say something like "Correct system time has to be restored manually > after resume." > instead of the second one. > Will do. I think I should add a check and print this warning when pm_trace is enabled and not when it is disabled. The way this patch is done, it prints this warning for enable and disable. For both: echo 1 > pm_trace and echo 0 > pm_trace. Any thoughts? -- Shuah Shuah Khan, Linux Kernel Developer - Open Source Group Samsung Research America (Silicon Valley) [email protected] | (970) 672-0658 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
