Re: [Crash-utility] [PATCH] printk: add support for lockless ringbuffer

-----Original Message----- > 在 2020年11月20日 13:56, HAGIO KAZUHITO(萩尾　一仁) 写道: > > From: John Ogness <john.ogness(a)linutronix.de&gt; > > > > Linux 5.10 introduces a new lockless ringbuffer. The new ringbuffer > > is structured completely different to the previous iterations. > > Add support for dumping the ringbuffer with the "log" command. > > The new ringbuffer is detected based on the availability of > > the "prb" symbol. > > > > Signed-off-by: John Ogness <john.ogness(a)linutronix.de&gt; > > Signed-off-by: Kazuhito Hagio <k-hagio-ab(a)nec.com&gt; > > --- > > I've updated John's RFC crash patch to match 5.10-rc4 kernel. > > Changes from the RFC patch: > > - followed the following kernel commits > > cfe2790b163a ("printk: move printk_info into separate array") > > 74caba7f2a06 ("printk: move dictionary keys to dev_printk_info") > > f35efc78add6 ("printk: remove dict ring") > > - moved the added members in offset_table and size_table to the end > > of them > > - print offsets and sizes with "help -o" option > > - support "log -T" option > > > > Thanks for the patch, Kazu and John. > > This patch looks good. Acked-by: Lianbo Jiang <lijiang(a)redhat.com&gt; OK, thanks. One thing, I found that caller_id can be raw_smp_processor_id() (see printk_caller_id()), so will modify a bit as follows when merging. --- a/printk.c +++ b/printk.c @@ -132,7 +132,8 @@ dump_record(struct prb_map *m, unsigned long id, int msg_flags) seq = ULONGLONG(info + OFFSET(printk_info_seq)); caller_id = UINT(info + OFFSET(printk_info_caller_id)); if (CRASHDEBUG(1)) - fprintf(fp, "seq: %llu caller_id: %u\n", seq, caller_id); + fprintf(fp, "seq: %llu caller_id: %x (%s: %u)\n", seq, caller_id, + caller_id & 0x80000000 ? "cpu" : "pid", caller_id & ~0x80000000); text_len = USHORT(info + OFFSET(printk_info_text_len)); Thanks, Kazu