linux-kernel - Re: [PATCH] printk: add early_counter

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Message-ID: <202511271051.yfp2O98B-lkp@intel.com>
Date: Thu, 27 Nov 2025 10:13:23 +0100
From: kernel test robot <lkp@...el.com>
To: Tim Bird <tim@...d.org>, pmladek@...e.com,
	Steve Rostedt <rostedt@...dmis.org>, john.ogness@...utronix.de,
	senozhatsky@...omium.org
Cc: oe-kbuild-all@...ts.linux.dev, Tim Bird <Tim.Bird@...y.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Memory Management List <linux-mm@...ck.org>,
	Francesco Valla <francesco@...la.it>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux Embedded <linux-embedded@...r.kernel.org>
Subject: Re: [PATCH] printk: add early_counter_ns routine for printk blind
 spot

Hi Tim,

kernel test robot noticed the following build errors:

[auto build test ERROR on linus/master]
[also build test ERROR on v6.18-rc7]
[cannot apply to akpm-mm/mm-everything next-20251127]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Tim-Bird/printk-add-early_counter_ns-routine-for-printk-blind-spot/20251125-133242
base:   linus/master
patch link:    https://lore.kernel.org/r/39b09edb-8998-4ebd-a564-7d594434a981%40bird.org
patch subject: [PATCH] printk: add early_counter_ns routine for printk blind spot
config: i386-randconfig-2006-20250825 (https://download.01.org/0day-ci/archive/20251127/202511271051.yfp2O98B-lkp@intel.com/config)
compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251127/202511271051.yfp2O98B-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202511271051.yfp2O98B-lkp@intel.com/

All errors (new ones prefixed by >>):

   ld: init/main.o: in function `kernel_init':
>> init/main.c:1522:(.ref.text+0x201): undefined reference to `__udivdi3'


vim +1522 init/main.c

  1481	
  1482	static int __ref kernel_init(void *unused)
  1483	{
  1484		int ret;
  1485		u64 end_cycles, end_ns;
  1486		u32 early_mult, early_shift;
  1487	
  1488		/*
  1489		 * Wait until kthreadd is all set-up.
  1490		 */
  1491		wait_for_completion(&kthreadd_done);
  1492	
  1493		kernel_init_freeable();
  1494		/* need to finish all async __init code before freeing the memory */
  1495		async_synchronize_full();
  1496	
  1497		system_state = SYSTEM_FREEING_INITMEM;
  1498		kprobe_free_init_mem();
  1499		ftrace_free_init_mem();
  1500		kgdb_free_init_mem();
  1501		exit_boot_config();
  1502		free_initmem();
  1503		mark_readonly();
  1504	
  1505		/*
  1506		 * Kernel mappings are now finalized - update the userspace page-table
  1507		 * to finalize PTI.
  1508		 */
  1509		pti_finalize();
  1510	
  1511		system_state = SYSTEM_RUNNING;
  1512		numa_default_policy();
  1513	
  1514		rcu_end_inkernel_boot();
  1515	
  1516		do_sysctl_args();
  1517	
  1518		/* show calibration data for early_counter_ns */
  1519		end_cycles = get_cycles();
  1520		end_ns = local_clock();
  1521		clocks_calc_mult_shift(&early_mult, &early_shift,
> 1522			((end_cycles - start_cycles) * NSEC_PER_SEC)/(end_ns - start_ns),
  1523			NSEC_PER_SEC, 50);
  1524	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki