From: Daniel Hellstrom <daniel@xxxxxxxxxxx> Date: Thu, 16 Dec 2010 15:24:02 +0100 > Why is IRQ15, the non-maskable IRQ, used for cross calls? Would it not > be safer to use IRQ14? > > Since IRQ15 is non-maskable it will even interrupt spin_lock_irqsave() > protected reqions. I assume it is safe as long as the cross call > function run in IRQ context does not try to take the same spinlock, > for that would create a dead lock I believe. For example atomic_add() > on SPARC32 below is implemented using one of four global spinlocks, > does that mean that we can not use atomic functions at all from within > a cross call function? We don't want operations like TLB and cache flushes to be blocked by IRQ disabling. For other operations, we should reschedule it to a software interrupt at a lower level than 15, but nobody has done the work to implement this yet. -- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
