On Wed, 31 Jan 2018 21:48:42 +0100, Chris Wilson
<chris@xxxxxxxxxxxxxxxxxx> wrote:
Quoting Michal Wajdeczko (2018-01-31 18:23:47)
Our inject_load_failure functionality allows to insert one
failure during driver load, but it is hard to guess which
number should passed as modparam to select specific checkpoint.
Use negative number as option to list all available failure
checkpoints without triggering any failure.
Hmm, it was only intended for use with the coupled igt test. Mind
expanding upon the use case you have? Could you not use that iterative
search for finding the injection value you want for repeated runs? For
the bisect case, do you not want to keep it iterating over all in case
the value changes? How stable do you want the modparam?
Iterative approach is good for validation team to verify that all
existing failure points are correctly handled (ie. we don't cause
crash/panic), but it is less useful when you are interested in adding
new checkpoints just for your code, as it requires both time and luck
as you may be hit by earlier checkpoint that no longer works ;)
Btw, IMHO this modparam should only be exposed in DEBUG config (as it
introduces some code and text), and maybe we should also consider
extending it to support more than one failure (as then it will be
easy to check several code paths (like failure in fallback)
This patch was trying to keep definition of modparam unchanged (extra
-1 value should not be noticed by any existing use case) but since
it is purely debug feature I'm not against making bigger changes here.
Michal
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