On Tue, Jun 16 2020 at 09:05AM -0700, Paul E. McKenney wrote:
> On Tue, Jun 16, 2020 at 11:49:24AM +0200, Marco Elver wrote:
> > We need to pass the arguments provided to --kmake-arg to all make
> > invocations. In particular, the make invocations generating the configs
> > need to see the final make arguments, e.g. if config variables depend on
> > particular variables that are passed to make.
> >
> > For example, when using '--kcsan --kmake-arg CC=clang-11', we would lose
> > CONFIG_KCSAN=y due to 'make oldconfig' not seeing that we want to use a
> > compiler that supports KCSAN.
> >
> > Signed-off-by: Marco Elver <elver@xxxxxxxxxx>
>
> Queued and pushed, thank you!
>
> Would the following patch make sense, at least until such time
> as some other compiler supports KCSAN?
>
> Thanx, Paul
>
> ------------------------------------------------------------------------
>
> commit 88bcaa730b6d40ddf69b09ed6f0a14803d087d99
> Author: Paul E. McKenney <paulmck@xxxxxxxxxx>
> Date: Tue Jun 16 09:02:34 2020 -0700
>
> torture: Make --kcsan default to using Clang 11
>
> Currently, Clang 11 is the only compiler that can support KCSAN.
> Therefore, as a convenience to the KCSAN user, this commit causes
> --kcsan to specify Clang 11 unless a "CC=" argument was already
> specified via the --kmake-arg argument.
As soon as more compilers support KCSAN (e.g. clang-12, etc...) we run
the risk of actually inconveniencing ourselves more because then we
really need to say '--kmake-arg CC=clang-1X' to not use the old
compiler. Or revert this in time.
My command-line looks more like this right now:
kvm.sh ... --kmake-arg "CC="${HOME}/local/<gcc-or-clang>-11.kcsan/local/bin/<gcc-or-clang>" ...
I think the safer alternative would be to error if CONFIG_KCSAN=y is not
in the config, and simply suggest "Did you forget to switch your
compiler with '--kmake-arg CC=<cc-that-supports-kcsan>'?" (of course, a
'gcc' in $PATH that supports KCSAN would also be fine -- see below).
Eventually, when the default compilers support KCSAN, this will resolve
itself gracefully.
Also, I'm going to send a series later this week to re-enable GCC
support. ;-)
Thanks,
-- Marco
