[Skiboot] trace settings

Stewart Smith stewart at linux.ibm.com
Fri Sep 14 15:23:15 AEST 2018

Raymond Higgs <raymond.higgs at broadcom.com> writes:
> Is it possible to change the trace settings without recompiling the
> firmware?  I'm interested in messages like this:
> [   90.072348476,5] OPAL skiboot-v6.0-p1da203b starting...
> [   90.072352660,7] initial console log level: memory 7, driver 5
> [   90.072354749,6] CPU: P9 generation processor (max 4 threads/core)
> [   90.072356576,7] CPU: Boot CPU PIR is 0x0014 PVR is 0x004e1202
> I wouldn't normally post to a development mailing list, but I have looked
> through a lot of documentation, and cannot find a procedure for this.

Yes, there is!

Hiding in possibly the *worst* place imaginable in the documentation

Is this:
console: Set log level from nvram

This adds two new nvram options to set the console log level for the
driver/uart and in memory. These are called log-level-memory and

These are only set once we have nvram inited.

To set them you do:

nvram -p ibm,skiboot --update-config log-level-memory=9
nvram -p ibm,skiboot --update-config log-level-driver=9

You can also use the named versions of emerg, alert, crit, err, warning,
notice, printf, info, debug, trace or insane. ie.

nvram -p ibm,skiboot --update-config log-level-driver=insane

So, if you run those and reboot, skiboot will do enhanced logging. I'd
*NOT* recommend trying Insane unless you are insane and know how to
clear your NVRAM out of band :)

The "memory" setting goes to the in memory buffer
(i.e. /sys/firmware/opal/msglog on a booted system) and the "driver" one
goes out to whatever driver we have hooked up (i.e. on that system it'll
be the IPMI console).

Note that the IPMI console is usually fairly slow, so outputting things
there *will* slow down boot.

Stewart Smith
OPAL Architect, IBM.

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