On Wed, Aug 16, 2017 at 9:46 PM, John Stultz <john.stultz@xxxxxxxxxx> wrote: > From: Prarit Bhargava <prarit@xxxxxxxxxx> > > > Prarit, > So I took my own shot at cleaning up the Kconfig settings to make > it a bit more sane in my opinion. This should allow the legacy > defconfigs to just work, and avoids all the defconfig churn in the > patch. > > I almost went through to try to simplify the code and make > PRINTK_TIME_DISABLE = 0 and to get rid of PRINTK_TIME_UNDEFINED, > as that seems like extra complexity that could probably be done > simpler, but I didn't quite have the time to get my head around > it all, so I left it be. But you might want to see if it can't > be further simplified (ie: initialize it to CONFIG_PRINTK_TIME_VAL > and then override it by the boot parameter if specified). > > Anwyay, let me know what you think, and feel free to adopt this > along with any other changes you have planned. > > thanks > -john > > > printk.time=1/CONFIG_PRINTK_TIME=1 adds a unmodified local hardware clock > timestamp to printk messages. The local hardware clock loses time each > day making it difficult to determine exactly when an issue has occurred in > the kernel log, and making it difficult to determine how kernel and > hardware issues relate to each other in real time. > > Make printk output different timestamps by adding options for no > timestamp, the local hardware clock, the monotonic clock, the boottime > clock, and the real clock. Allow a user to pick one of the clocks by > using the printk.time kernel parameter. Output the type of clock in > /sys/module/printk/parameters/time so userspace programs can interpret the > timestamp. > > Real clock & 32-bit systems: Selecting the real clock printk timestamp may > lead to unlikely situations where a timestamp is wrong because the real time > without the protection of a sequence lock when printk_get_ts() is set > printk_get_real_ns(). > > v2: Use peterz's suggested Kconfig options. Merge patchset together. > Fix i386 !CONFIG_PRINTK builds. > > v3: Fixed x86_64_defconfig. Added printk_time_type enum and > printk_time_str for better output. Added BOOTTIME clock functionality. > > v4: Fix messages, add additional printk.time options, and fix configs. > > v5: Renaming of structures, and allow printk_time_set() to > evaluate substrings of entries (eg: allow 'r', 'real', 'realtime'). From > peterz, make fast functions return 0 until timekeeping is initialized > (removes timekeeping_active & ktime_get_boot|real_log_ts() suggested by > tglx and adds ktime_get_real_offset()). Switch to a function pointer > for printk_get_ts() and reference fast functions. Make timestamp_sources enum > match choice options for CONFIG_PRINTK_TIME (adds PRINTK_TIME_UNDEFINED). > > v6: Define PRINTK_TIME_UNDEFINED for !CONFIG_PRINTK builds. Separate > timekeeping changes into separate patch. Minor include file cleanup. > > Signed-off-by: Prarit Bhargava <prarit@xxxxxxxxxx> > Cc: Mark Salyzyn <salyzyn@xxxxxxxxxxx> > Cc: Jonathan Corbet <corbet@xxxxxxx> > Cc: Petr Mladek <pmladek@xxxxxxxx> > Cc: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx> > Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> > Cc: John Stultz <john.stultz@xxxxxxxxxx> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Cc: Stephen Boyd <sboyd@xxxxxxxxxxxxxx> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx> > Cc: Christoffer Dall <cdall@xxxxxxxxxx> > Cc: Deepa Dinamani <deepa.kernel@xxxxxxxxx> > Cc: Ingo Molnar <mingo@xxxxxxxxxx> > Cc: Joel Fernandes <joelaf@xxxxxxxxxx> > Cc: Prarit Bhargava <prarit@xxxxxxxxxx> > Cc: Kees Cook <keescook@xxxxxxxxxxxx> > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > Cc: Geert Uytterhoeven <geert+renesas@xxxxxxxxx> > Cc: "Luis R. Rodriguez" <mcgrof@xxxxxxxxxx> > Cc: Nicholas Piggin <npiggin@xxxxxxxxx> > Cc: "Jason A. Donenfeld" <Jason@xxxxxxxxx> > Cc: Olof Johansson <olof@xxxxxxxxx> > Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> > Cc: linux-doc@xxxxxxxxxxxxxxx > [jstultz: reworked Kconfig settings to avoid defconfig noise] > Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx> > --- > Documentation/admin-guide/kernel-parameters.txt | 6 +- > include/linux/timekeeping.h | 1 + > kernel/printk/printk.c | 147 +++++++++++++++++++++++- > kernel/time/timekeeping.c | 5 + > lib/Kconfig.debug | 54 ++++++++- > 5 files changed, 205 insertions(+), 8 deletions(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index d9c171c..1ba277e 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -3188,8 +3188,10 @@ > ratelimit - ratelimit the logging > Default: ratelimit > > - printk.time= Show timing data prefixed to each printk message line > - Format: <bool> (1/Y/y=enable, 0/N/n=disable) > + printk.time= Show timestamp prefixed to each printk message line > + Format: <string> > + (0/N/n/disable, 1/Y/y/local, > + b/boot, m/monotonic, r/realtime) > > processor.max_cstate= [HW,ACPI] > Limit processor to maximum C-state > diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h > index ddc229f..80ca2fa 100644 > --- a/include/linux/timekeeping.h > +++ b/include/linux/timekeeping.h > @@ -239,6 +239,7 @@ static inline u64 ktime_get_raw_ns(void) > extern u64 ktime_get_mono_fast_ns(void); > extern u64 ktime_get_raw_fast_ns(void); > extern u64 ktime_get_boot_fast_ns(void); > +extern u64 ktime_get_real_offset(void); > > /* > * Timespec interfaces utilizing the ktime based ones > diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c > index fc47863..fe208dc 100644 > --- a/kernel/printk/printk.c > +++ b/kernel/printk/printk.c > @@ -576,6 +576,9 @@ static u32 truncate_msg(u16 *text_len, u16 *trunc_msg_len, > return msg_used_size(*text_len + *trunc_msg_len, 0, pad_len); > } > > +static u64 printk_set_timestamp(void); > +static u64 (*printk_get_ts)(void) = printk_set_timestamp; > + > /* insert record into the buffer, discard old ones, update heads */ > static int log_store(int facility, int level, > enum log_flags flags, u64 ts_nsec, > @@ -624,7 +627,7 @@ static int log_store(int facility, int level, > if (ts_nsec > 0) > msg->ts_nsec = ts_nsec; > else > - msg->ts_nsec = local_clock(); > + msg->ts_nsec = printk_get_ts(); > memset(log_dict(msg) + dict_len, 0, pad_len); > msg->len = size; > > @@ -1202,14 +1205,141 @@ static inline void boot_delay_msec(int level) > } > #endif > > -static bool printk_time = IS_ENABLED(CONFIG_PRINTK_TIME); > -module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR); > +static int printk_time = CONFIG_PRINTK_TIME_VAL; Crud.. That should be CONFIG_PRINTK_TIME_TYPE. Apologies, forgot to commit that bit. thanks -john -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
