Rewrite the ARM mutex implementation to be of the simple-mutex variety.
Because pre-v6 ARM lacks support for an atomic compare-and-swap, we
implement _lock_cas() as a restartable atomic squence that is checked
in the IRQ handler right before AST processing. (This is safe because,
for all practical purposes, there are no SMP pre-v6 ARM systems.)
This can serve as a model for other non-MP platforms that lack the
necessary atomic operations for mutexes (SuperH, for example).
Upshots of this change:
- kmutex_t is now down to 8 bytes on ARM; about as good as we can get.
- ARM2 systems don't have to trap and emulate SWP or SWPB for mutexes.
The acorn26 port is not updated by this commit to do the LOCK_CAS_CHECK.
That is left as an exercise for the port maintainer.
Reviewed and tested by Matt Thomas.
Because pre-v6 ARM lacks support for an atomic compare-and-swap, we
implement _lock_cas() as a restartable atomic squence that is checked
in the IRQ handler right before AST processing. (This is safe because,
for all practical purposes, there are no SMP pre-v6 ARM systems.)
This can serve as a model for other non-MP platforms that lack the
necessary atomic operations for mutexes (SuperH, for example).
Upshots of this change:
- kmutex_t is now down to 8 bytes on ARM; about as good as we can get.
- ARM2 systems don't have to trap and emulate SWP or SWPB for mutexes.
The acorn26 port is not updated by this commit to do the LOCK_CAS_CHECK.
That is left as an exercise for the port maintainer.
Reviewed and tested by Matt Thomas.
merge link_set_* sections into the text section for a.out kernels,
from sys/arch/arm/conf/ to sys/conf/ since there is no ARM specific
stuff in it and other ports would share it.
the latest ABLE firmware was causing an interrupt mapping issue on cats.
It seems that the latest ABLE firmware is using native-PCI mode, rather
than compatibility mode, but doesn't setup an irq for us to use, so we fail
to map the interrupt handler.
with newlock2 merge:
Replace the Mach-derived boolean_t type with the C99 bool type. A
future commit will replace use of TRUE and FALSE with true and false.
int _bus_dmatag_subregion(bus_dma_tag_t tag,
bus_addr_t min_addr,
bus_addr_t max_addr,
bus_dma_tag_t *newtag,
int flags)
void _bus_dmatag_destroy(bus_dma_tag_t tag)
that allow a (normally broken/limited) device to restrict the bus address
range it can talk to. this is used by bce(4) to limit DMA addresses to
1GB range, the maximum the chip can address.
all this is from Yorick Hardy <yhardy@uj.ac.za> with input from several
people on tech-kern.
XXX: bus_dma(9) needs an update still.
ad