Messages in this thread | | | From | 김창기 <> | Subject | RE: printk: Add process name information to printk() output. | Date | Mon, 7 Sep 2020 10:48:16 +0900 |
| |
> On Fri, Sep 04, 2020 at 06:31:13PM +0900, â wrote: > > > On Fri, Sep 04, 2020 at 05:24:38PM +0900, Changki Kim wrote: > > > > Printk() meesages are the most basic and useful debug method. > > > > However, additional information needs in multi-processor. > > > > If we add messages with processor id and process name, we can find > > > > a problem only with messages when the problem occurs with H/W IP or > CPU. > > > > This is very useful in narrowing down the scope of the problems. > > > > > > > > Therefore, instead of trying to help buffering, let's try to help > > > > reconstructing messages by saving caller information as of calling > > > > log_store() and adding it as "[$processor_id: $process_name: > > > $thread_id]" > > > > upon printing to consoles. > > > > > > > > Some examples for console output: > > > > > > > > [ 0.059580] [0: swapper/0: 1] CPU: All CPU(s) started at > > EL1i > > > > [ 2.153157] [5: init: 1] migov: complete to probe > > migov > > > > [ 7.441317] [4: init: 1] NET: Registered protocol > > family 39 > > > > [ 22.793389] [5: kworker/u16:1: 184] SMP: stopping secondary > CPUs > > > > > > > > Signed-off-by: Changki Kim <changki.kim@samsung.com> > > > > --- > > > > kernel/printk/printk.c | 20 ++++++++++++++++++-- > > > > kernel/printk/printk_ringbuffer.h | 7 +++++++ > > > > lib/Kconfig.debug | 16 ++++++++++++++++ > > > > 3 files changed, 41 insertions(+), 2 deletions(-) > > > > > > Isn't the CPU number already present if you want it today? Why add > > > it again? > > > > > > thanks, > > > > > > greg k-h > > > > CPU number isn't present now. If I enabled PRINTK_CALLER, then it is > > present cpu id or thread id. > > Great, that should give you what you need here, right? > > > The config isn't always present cpu id. > > What do you mean?
When PRINTK_CALLER is enabled, cpu id or thread id are present. not always cpu id. > > > We need cpu id each each message. > > Why each message? What does that provide you?
In mobile project, Sometimes we can meet the problem in the physically cpu. It is important to know cpu id for H/W Issue. > > And if PRINTK_CALLER does not work properly, please fix it. I don't see > how it would not work any different from your patch, you shouldn't > duplicate things.
PRINTK_CALLER worked well. > > thanks, > > greg k-h
| |