Re: Get rid of Java .jcr section when not using Java

[Jonathan Wakely <jwakely dot gcc at gmail dot com>]

On 25 April 2017 at 20:04, Johannes Bauer wrote:
> Hi there,
>
> I'm using gcc-6.3.0 with the arm-non-eabi target and cross compile for
> ARM Cortex-M4. I've just traced an annoyingly elusive issue which
> ultimately turned out to be caused by a .jcr section that originates
> from gccs CRT. Note that I'm compiling bare metal Cortex-M, so I'm a
> million miles away from anything Javaish. There should not be a
> Java-related section consuming RAM on my microcontroller, in my opinion.
>
> When I turn on section garbage collection, it goes away (never
> referenced, obviously) but in this particular instance, I cannot turn on
> section GC. When I try to discard the section via my linker script, I
> get complaints:
>
> `.jcr' referenced in section `.text' of
> /home/joe/bin/gcc-cm4/lib/gcc/arm-none-eabi/6.3.0/crtbegin.o: defined in
> discarded section `.jcr' of
> /home/joe/bin/gcc-cm4/lib/gcc/arm-none-eabi/6.3.0/crtbegin.o
> collect2: error: ld returned 1 exit status
>
> I'm not the first to encounter this issue, but it doesn't seem to cause
> a problem for most people. E.g., I've found this here:
>
> https://gcc.gnu.org/ml/gcc-patches/2013-10/msg00654.html
>
> But it doesn't really apply to fixing this.

Why not?

> Since I do bake my own gcc flavor, I would also be happy with a solution
> that'd involve patching around gcc guts, but I'm just too clueless to
> know what to touch there.

Doesn't the patch show what to change?  #undef JCR_SECTION_NAME in
libgcc/crtstuff.c (although it looks like the macro has been renamed
to __LIBGCC_JCR_SECTION_NAME__).