[PATCH] utrace_control: return -EINVAL for missing UTRACE_EVENT(QUIESCE)

[Frank Ch. Eigler]

Hi -

> [...] I'm not sure what you mean here about "always correct".  It is
> always correct that you should not use UTRACE_SINGLESTEP without
> setting up a callback.  [...]

I wonder if utrace could be more helpful here.  If an engine just
wants to single-step from some other callback, forcing it to have a
quiesce callback just to re-re-re-repeat what it already asked for
seems like make-work.  Could utrace instead remember the last
instruction received either via utrace_control() or from a real
callback, and have utrace supply a dummy echo-bot quiesce?

- FChE