mjb/altos/src/stmf0/Makefile-stmf0.defs, branch debian/1.6.8-4AltOS - the operating system for Altus Metrum products
https://git.ethernal.org/mjb/altos/atom?h=debian%2F1.6.8-42017-01-25T19:21:43+00:00altos/arm: Align data so that gcc 5.4 doesn't do byte-accesses. Add -Wcast-align2017-01-25T19:21:43+00:00Keith Packardkeithp@keithp.com2016-12-18T04:58:36+00:00urn:sha1:fe25510fc23031f1a3c1b42edd37067d1989a9f6
Gcc 5.4.1 tracks alignment of data through assignments, so that a
uint32_t pointer which comes from byte-aligned uint8_t data:
extern uint8_t foo[];
uint32_t *q = (void *) foo;
Fetches and stores through this pointer are done bytewise. This is
slow (meh), but if q references a device register, things to bad very
quickly.
This patch works around this bug in the compiler by adding
__attribute__((aligned(4))) tags to some variables, or changing them
from uint8_t to uint32_t. Places doing this will now be caught as I've
added -Wcast-align to the compiler flags. That required adding (void
*) casts, after the relevant code was checked to make sure the
compiler could tell that the addresses were aligned.
Signed-off-by: Keith Packard <keithp@keithp.com>
altos: Initial STMF04x support2015-01-26T00:42:39+00:00Keith Packardkeithp@keithp.com2015-01-26T00:42:39+00:00urn:sha1:02f03df6d089cafae99f8ce15dcbd87f6e78d749
Basic clock configuration, OS support, LED and USB drivers.
Signed-off-by: Keith Packard <keithp@keithp.com>