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authorUwe Bonnes2013-01-21 13:50:02 +0100
committerUwe Bonnes2013-01-21 13:52:02 +0100
commit29fc42e4198029bb958d9feb68787b9d2eeb124f (patch)
treed2e420e4224e97b0baea0d579bbf4bc007657dfc /HACKING
parent747cc58c2c57f259430eeede8386be4214d00c9d (diff)
Add note about -mfloat-abi=hard versus -mfloat-abi=soft
Diffstat (limited to 'HACKING')
-rw-r--r--HACKING10
1 files changed, 10 insertions, 0 deletions
diff --git a/HACKING b/HACKING
index e79d573..ee1fc24 100644
--- a/HACKING
+++ b/HACKING
@@ -44,6 +44,16 @@ over USB:
The device should reset and re-enumerate as a CDC-ACM device implementing
the GDB protocol.
+Errors when compiling libopencm3
+-------------------------------
+If while compiling libopencm3 you get an error like
+arm-none-eabi/bin/ld: error: cdcacm.elf uses VFP register arguments, \
+ arm-none-eabi/lib/thumb/v7m/libc.a(lib_a-memcpy-stub.o) does not
+your toolchain and libopencm3 disagree on the calling convention for floation
+point functions on the F4. Change in
+lib/stm32/f4/Makefile and examples/stm32/f4/Makefile.include all apperance of
+-mfloat-abi=hard to -mfloat-abi=soft
+This doesn't matter for blackmagic, as it doesn't use floating point.
Compiling as a Linux application using FT2232 hardware
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