On 08/13/2014 05:05 PM, Khem Raj wrote:
On Wed, Aug 13, 2014 at 2:36 PM, Peter A. Bigot <p...@pabigot.com> wrote:
In any case, Khem can you run with this? It'd be fixed a lot better that
way....
We do not configure target gcc with right matching cpu defaults,
atomic instruction strex/ldrex are only added after armv6 but defaults
for gcc if not specified is armv5t and hence it does not use the right
set as expected by libstdc++ which has been cross compiled. so while
you are at it and can reproduce it. Try to add
EXTRA_OECONF += '${@bb.utils.contains("TUNE_FEATURES", "armv7a", "
--with-cpu=armv7-a", "", d)}'
to gcc-target.inc and see if resulting gcc is any better
I had to make it:
EXTRA_OECONF += '${@bb.utils.contains("TUNE_FEATURES", "armv7a",
"--with-cpu=generic-armv7-a", "", d)}'
to get gcc to build but at runtime I then get:
beaglebone[16]$ g++ -std=c++11 -pthread test.cc && ./a.out
Assembler messages:
Error: unknown cpu `generic-armv7-a'
Error: unrecognized option -mcpu=generic-armv7-a
which indicates the flag's being passed to the assembler which doesn't
recognize it even though g++ is happy with it. I suppose we could hack
binutils to substitute whatever spelling it wants to see.
(Also tried --with-cpu=arm7, but that generates assembler errors related
to unsupported RM mode "bx lr").
The approach bothers me, though. Instead of explicitly changing
gcc-target to match gcc-runtime, shouldn't it be a general rule that
gcc-runtime not apply OE-specific target flags that aren't going to be
used by direct invocations of the compiler outside of the OE build
environment? That seems a little more robust, as the default target
flags may be changed upstream or by bbappends within OE, and having to
make them match in gcc-runtime as well would be a headache.
And would we need similar overrides for other architectures? There's
something similar already in gcc-configure-common.inc for mips64.
Peter
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