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[build] Fix use of inline assembly on GCC 4.8 ARM64 builds
The inline assembly used in include/errno.h to generate the einfo
blocks requires the ability to generate an immediate constant with no
immediate-value prefix (such as the dollar sign for x86 assembly).

We currently achieve this via the undocumented "%c0" form of operand.
This causes an "invalid operand prefix" error on GCC 4.8 for ARM64
builds.

Fix by switching to the equally undocumented "%a0" form of operand,
which appears to work correctly on all tested versions of GCC.

Reported-by: Benjamin S. Allen <bsallen@alcf.anl.gov>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
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mcb30 committed Jul 28, 2017
1 parent b6fc8be commit 1a77466
Showing 1 changed file with 2 additions and 2 deletions.
4 changes: 2 additions & 2 deletions src/include/errno.h
Expand Up @@ -262,10 +262,10 @@ static inline void eplatform_discard ( int dummy __unused, ... ) {}
".align 8\n\t" \
"\n1:\n\t" \
".long ( 4f - 1b )\n\t" \
".long %c0\n\t" \
".long %a0\n\t" \
".long ( 2f - 1b )\n\t" \
".long ( 3f - 1b )\n\t" \
".long %c1\n\t" \
".long %a1\n\t" \
"\n2:\t.asciz \"" __einfo_desc ( einfo ) "\"\n\t" \
"\n3:\t.asciz \"" __FILE__ "\"\n\t" \
".align 8\n\t" \
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