Subject: Re: SMP re-eetrancy in "bottom half" drivers
To: None <>
From: YAMAMOTO Takashi <>
List: tech-net
Date: 05/17/2005 17:30:10

>    (Note that some "SMP-safe" drivers will need to acquire the
>    big-lock, e.g., drivers layerd over serial, IPL_TTY devices)

i think you misunderstood what i meant in the private mail.

what i meant is, even if you made all network drivers "smp-safe",
you still need to grab biglock for them because they can be
interrupted by higher level interrupts which need biglock.
ie. in the case of i386, it's better to tackle audio drivers first.

alternatives i can think of are:

	- introduce some magic in md intr code to determine
	  the highest level IPL which needs biglock dynamically.
	  (device hotplug nightmare?)

	- obsolete IPLs.
	  (like freebsd.  i think my old patch contains an equivalent hack.)