RE: [OE-core] [PATCH] cmake: read asm flags correctly from environment in toolchain file

[Peter Kjellerstedt <peter.kjellerstedt@axis.com>]

> -----Original Message-----
> From: openembedded-core@lists.openembedded.org <openembedded-
> core@lists.openembedded.org> On Behalf Of Martin Beeger
> Sent: den 14 februari 2022 17:32
> To: Richard Purdie <richard.purdie@linuxfoundation.org>; openembedded-
> core@lists.openembedded.org
> Subject: Re: [OE-core] [PATCH] cmake: read asm flags correctly from
> environment in toolchain file
> 
> 
> > I'm a little more puzzled on this one since whilst we set CFLAGS and
> CXXFLAGS in
> > bitbake.conf, we don't set ASMFLAGS and it wouldn't be present in our
> > environment.
> >
> > Perhaps this should be $ENV{CFLAGS} instead of ${CMAKE_C_FLAGS}? There
> are flags
> > in our CFLAGS which like need to be passed to the assembler too?
> 
> I am a bit unsure now about this.
> As far as I understand the environment-setup will not set ASMFLAGS, that
> is correct. For all non-cmake recipes, the compiler will not pick up
> CFLAGS instead. It will simply still use no extra parameters for the
> inline assembly.
> In cmake it will use the CFLAGS for the ASM too, yielding inconsistent
> behaviour over build systems. Is that really a good thing?
> 
> Also the CFLAGS are usually "-O2 -g". At least the -g parameter will
> have limited effect for the assembly, and optimizations for inline
> assembly are also extremely limited.
> So the practical difference between both modes and whether the flags
> propagate through is minimal, if at all existent.
> 
> All critical compiler parameters like the --sysroot and others are not
> stored in CFLAGS, but are instead directly appended to the compiler
> executable path for CC, CXX and so on. These are always applied and
> cmake does understand these, parses them out, forces them to always be
> there etc.
> This code has nothing to do with that, it only impacts the optimization
> and debugging flags.
> 
> This patch makes this behaviour consistent between cmake and non-cmake
> recipes in that is never applies ASM flags, instead of inconsistently
> applying them.

For the record, the variable name that, e.g., make expects for assembler 
flags in its default rules is "ASFLAGS", not "ASMFLAGS".

//Peter