[Intel-gfx] [PATCH] ftrace: Allow configuring global trace buffer size (for dump-on-oops)

[Chris Wilson]

Quoting Chris Wilson (2017-11-13 13:07:08)
> We have recently turned on ftrace-dump-on-oops for i915's CI and an
> issue we have encountered is that the trace buffer size greatly exceeds
> the pstore capabilities; we get the tail of the oops but not the
> introduction.
> 
> Currently the global buffer size is controllable on the cmdline, but at
> the request of our CI sysadmin, we would like to add a control to the
> Kconfig as well. The rationale being the cmdline carries the temporary
> hacks that we want to eradicate, and we want to track the permanent
> configuration in .config.
> 
> I have kept the Kconfig option hidden from the user as the default
> should suffice for the majority of users; reserving the configuration
> for those that eschew the cmdline option.

Odd, by removing the prompt the default value will always override the
user value in .config.

I had to restore a 
	prompt "Global ftrace buffer size" if EXPERT
to keep it configurable.
-Chris