[uClinux-dev] Re: soft_irq()

John Willlams jwilliams at itee.uq.edu.au
Mon Mar 24 06:17:44 EST 2003


Hi Miles,

From: Miles Bader <miles at lsi.nec.co.jp>

>So (as far as I understand things -- salt liberally!), a typical device
>interrupt handler might would twiddle a few bits, update some critical
>pointers, schedule a softirq to do anything more time-consuming, and
>then return.  The soft-irq it scheduled would then get run just before
>returning from the outermost interrupt level.

Sounds reasonable, and just like the "top half/bottom half" interrupt
handling that is talked about in my linux kernel book (2.0 oriented).

Still, I'm curious as to why I'm getting a softirq scheduled, apparently  by
my timer interrupt handler (nothing else is running, I'm still in the kernel
"dark ages"!)

I've hacked all this stuff straight out of your v850 code and I've seen
nothing to suggest it in there.  I'm wondering if I'm failing to properly
initialise whatever data structure is queried by the softirq_pending()
macro.

There must be an equivalent "schedule_softirq()" macro somewhere, I'll dig
it out tomorrow and see what I can find.

Cheers,

John




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