Re: [PATCH v2 2/2] tools/memory-model: Make ppo a subrelation of po

Andrea Parri
2023-01-28T22:14:31Z

> Evidently the plain-coherence check rules out x=1 at the
> end, because when I relax that check, x=1 becomes a possible result.
> Furthermore, the graphical output confirms that this execution has a
> ww-incoh edge from Wx=2 to Wx=1. But there is no ww-vis edge from Wx=1
> to Wx=2! How can this be possible? It seems like a bug in herd7.

By default, herd7 performs some edges removal when generating the
graphical outputs. The option -showraw can be useful to increase
the "verbosity", for example,

[with "exists (x=2)", output in /tmp/T.dot]
$ herd7 -conf linux-kernel.cfg T.litmus -show prop -o /tmp -skipchecks plain-coherence -doshow ww-vis -showraw ww-vis

> Furthermore, the execution with x=2 at the end doesn't have either a
> ww-vis or a ww-nonrace edge betwen Wx=1 and Wx=2. So why isn't there a
> ww-race edge?

And similarly

[with "exists (x=2)"]
$ herd7 -conf linux-kernel.cfg T.litmus -show prop -o /tmp -doshow ww-vis,ww-nonrace -showraw ww-vis,ww-nonrace

Andrea