Messages in this thread |  | | Date | Mon, 13 May 1996 21:24:42 +0200 (MET DST) | From | Ingo Molnar <> | Subject | fast_IRQ##_interrupt() Question(s) |
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in arch/asm-i386/irq.h,
A) every interrupt handler starts with code like this:
SAVE_MOST \ ACK_##chip(mask) \
is there any gain in splitting "SAVE_MOST" into two parts, to ACK the PIC[s] earlier?:
SAVE_EAX \ <----------- since AL gets clobbered in ACK_##chip(mask) ACK_##chip(mask) \ <----- hey, we've acked the irq a few cycles earlier :) SAVE_MOST_BUT_EAX \ <----- here we save the rest
B) and a related question. The slow interrupt handlers start with this code:
SYMBOL_NAME_STR(IRQ) #nr "_interrupt:\n\t" \ "pushl $-"#nr"-2\n\t" \
why is "-nr-2" pushed to the stack? A few lines later we do:
"pushl $" #nr "\n\t" \
which is "nr" to the stack. my best guess is that this is some kind identification. But why twice?
-- a slightly puzzled mingo
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