On Wed, May 05, 2021 at 10:22:57AM +0100, Alex Bennée wrote: > Currently attempts to add a new TCG trace events results in failures > to build. Previous discussions have suggested maybe it's time to mark > the feature as deprecated and push people towards using plugins. > > Signed-off-by: Alex Bennée <alex.bennee(a)linaro.org&gt; > Cc: Luis Vilanova <vilanova(a)imperial.ac.uk&gt; > Cc: Stefan Hajnoczi <stefanha(a)redhat.com&gt; > --- > docs/devel/tcg-plugins.rst | 2 ++ > docs/devel/tracing.rst | 7 +++++++ > docs/system/deprecated.rst | 13 +++++++++++++ > 3 files changed, 22 insertions(+) > > diff --git a/docs/devel/tcg-plugins.rst b/docs/devel/tcg-plugins.rst > index 18c6581d85..edf04e3091 100644 > --- a/docs/devel/tcg-plugins.rst > +++ b/docs/devel/tcg-plugins.rst > @@ -3,6 +3,8 @@ > Copyright (c) 2019, Linaro Limited > Written by Emilio Cota and Alex Bennée > > +.. _tcgplugin-ref: > + > ================ > QEMU TCG Plugins > ================ > diff --git a/docs/devel/tracing.rst b/docs/devel/tracing.rst > index ba83954899..6b0f46cd54 100644 > --- a/docs/devel/tracing.rst > +++ b/docs/devel/tracing.rst > @@ -414,6 +414,13 @@ disabled, this check will have no performance impact. > "tcg" > ----- > > +.. warning:: > + The ability to add new TCG trace points relies on a having a good > + understanding of the TCG internals. In the meantime TCG plugins > + have been introduced which solve many of the same problems with > + more of a focus on analysing guest code. See :ref:`tcgplugin-ref` > + for more details. > + > Guest code generated by TCG can be traced by defining an event with the "tcg" > event property. Internally, this property generates two events: > "<eventname>_trans" to trace the event at translation time, and > diff --git a/docs/system/deprecated.rst b/docs/system/deprecated.rst > index 80cae86252..0c9d3c1e1e 100644 > --- a/docs/system/deprecated.rst > +++ b/docs/system/deprecated.rst > @@ -312,6 +312,19 @@ The ``I7200`` guest CPU relies on the nanoMIPS ISA, which is deprecated > (the ISA has never been upstreamed to a compiler toolchain). Therefore > this CPU is also deprecated. > > +TCG introspection features > +-------------------------- > + > +TCG trace-events (since 6.1) > +'''''''''''''''''''''''''''' > + > +The ability to add new TCG trace points has bit rotted and as the When you say this "has bit rotted", just how bad is the situation ? Is the TCG tracing still usable at all, or is is fully broken already ?

> +feature can be replicated with TCG plugins it will be deprecated. If > +any user is currently using this feature and needs help with > +converting to using TCG plugins they should contact the qemu-devel > +mailing list. > + Regards, Daniel