On 2020-01-24 01:19, Stephen Boyd wrote:
Quoting Sai Prakash Ranjan (2020-01-23 08:00:31)
Since commit f92b070f2dc8 ("printk: Do not miss new messages
when replaying the log"), CON_PRINTBUFFER flag causes the
duplicate boot messages to be printed on the console when
PSTORE_CONSOLE and earlycon (boot console) is enabled.
Pstore console registers to boot console when earlycon is
enabled during pstore_register_console as a part of ramoops
initialization in postcore_initcall and the printk core
checks for CON_PRINTBUFFER flag and replays the log buffer
to registered console (in this case pstore console which
just registered to boot console) causing duplicate messages
to be printed. Remove the CON_PRINTBUFFER flag from pstore
console since pstore is not concerned with the printing of
buffer to console but with writing of the buffer to the
backend.
Console log with earlycon and pstore console enabled:
[ 0.008342] Console: colour dummy device 80x25
[ 0.000000] Booting Linux on physical CPU 0x0000000000 [0x51df805e]
...
[ 1.244049] hw-breakpoint: found 6 breakpoint and 4 watchpoint
registers.
[ 0.000000] Booting Linux on physical CPU 0x0000000000 [0x51df805e]
Fixes: f92b070f2dc8 ("printk: Do not miss new messages when replaying
the log")
Reported-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
---
While I like the idea, it seems that this breaks console-ramoops by
removing all the text that is printed in the kernel log before this
console is registered. I reboot and see that
/sys/fs/pstore/console-ramoops-1 starts like this now:
localhost ~ # cat /sys/fs/pstore/console-ramoops-0
[ 0.943472] printk: console [pstore-1] enabled
Maybe this console can be "special" and not require anything to be
printed out to visible consoles but still get the entire log contents?
Or we should just not worry about it.
Thanks for testing this out Stephen, I should have tested this some
more.
Lets drop this patch.
-Sai
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