On 30 August 2017 at 19:16, Michael Ellerman <m...@ellerman.id.au> wrote: > Joe Stringer <j...@ovn.org> writes: > >> On 30 August 2017 at 15:59, Andrew Morton <a...@linux-foundation.org> wrote: >>> On Tue, 29 Aug 2017 16:01:14 -0700 Joe Stringer <j...@ovn.org> wrote: >>> >>>> Recent changes[0] to make use of __compiletime_assert() from >>>> container_of() increased the usage of this macro, allowing developers to >>>> notice type conflicts in usage of container_of() at compile time. >>>> However, the implementation of __compiletime_assert relies on compiler >>>> optimizations to report an error. This means that if a developer uses >>>> "-O0" with any code that performs container_of(), the compiler will >>>> always report an error regardless of whether there is an actual problem >>>> in the code. >>>> >>>> This patch disables compile_time_assert when optimizations are disabled >>>> to allow such code to compile with CFLAGS="-O0". >>> >>> I'm wondering if we should backport this into -stable. Probably not, >>> as I doubt if many people use -O0 - it's a pretty weird thing to do. I >>> used to use it a bit because it makes the ".lst" files (intermingled .c >>> and .s files) make more sense. In fact I'm wondering how you even >>> noticed this? >> >> Local debugging, was trying to get a better understanding of the >> underlying assembly and the code I was using just happened to use >> container_of(). > > Does the kernel actually build with -O0? I didn't think it actually > worked.
I haven't tried the whole kernel, but you can set these CFLAGS on specific files with a one-liner in a makefile: CFLAGS_foo.o = -O0
