165d4e6d83
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. |
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| .. | ||
| files.ofw | ||
| files.ofwgencfg | ||
| ofw_irq.S | ||
| ofw_irqhandler.c | ||
| ofwgencfg_clock.c | ||
| ofwgencfg_machdep.c | ||
| openfirm.c | ||