Hi Tetsuo, Thanks for implementing this, it's really helpful.
Tetsuo Handa <[email protected]> writes: ... > From 91f85d2bd494df2f73c605d8b4747e8cc0a61ae2 Mon Sep 17 00:00:00 2001 > From: Tetsuo Handa <[email protected]> > Date: Tue, 18 Dec 2018 05:53:04 +0900 > Subject: [PATCH] printk: Add caller information to printk() output. > > Sometimes we want to print a series of printk() messages to consoles > without being disturbed by concurrent printk() from interrupts and/or > other threads. But we can't enforce printk() callers to use their local > buffers because we need to ask them to make too much changes. Also, even > buffering up to one line inside printk() might cause failing to emit > an important clue under critical situation. > > 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 "[T$thread_id]" or "[C$processor_id]" > upon printing to consoles. > > Some examples for console output: > > [ 1.222773][ T1] x86: Booting SMP configuration: > [ 2.779635][ T1] pci 0000:00:01.0: PCI bridge to [bus 01] > [ 5.069193][ T268] Fusion MPT base driver 3.04.20 > [ 9.316504][ C2] random: fast init done > [ 13.413336][ T3355] Initialized host personality > > Some examples for /dev/kmsg output: > > 6,496,1222773,-,caller=T1;x86: Booting SMP configuration: > 6,968,2779635,-,caller=T1;pci 0000:00:01.0: PCI bridge to [bus 01] > SUBSYSTEM=pci > DEVICE=+pci:0000:00:01.0 > 6,1353,5069193,-,caller=T268;Fusion MPT base driver 3.04.20 > 5,1526,9316504,-,caller=C2;random: fast init done > 6,1575,13413336,-,caller=T3355;Initialized host personality > > Note that this patch changes max length of messages which can be printed > by printk() or written to /dev/kmsg interface from 992 bytes to 976 bytes, > based on an assumption that userspace won't try to write messages hitting > that border line to /dev/kmsg interface. Do you have any plans to update dmesg or other userspace tools to show the caller information? cheers
