Subject: Re: SMP re-eetrancy in "bottom half" drivers
To: YAMAMOTO Takashi <>
From: Jonathan Stone <>
List: tech-net
Date: 05/17/2005 15:14:14
In message <>,
YAMAMOTO Takashi writes:

>how ASIDs are related?
>normally interrupt threads shouldn't need to switch address space for
>i386 or amd64.

Yes, you do, if the CPU was previously in userspace (or in process
context doing a copyin/copyout), and you choose to handle interrupts
by context-switching to a separate kthread (or moral equivalent).
The  low-level ``interrupt''  hanlder merely schedules the appropriate
interrupt-handling thread.

From Stephan's message (and independenlty, from prior conversations
with FreeBSD-5 experts), I beleive that's essentially what FreeBSD-5 does.

If I'm mistaken, I look forward to being gently clue-by-four'ed.