Subject: Re: FreeBSD's /dev on NetBSD
To: None <>
From: Hans Petter Selasky <>
List: tech-kern
Date: 08/14/2005 00:09:59
On Saturday 13 August 2005 21:29, Nathan J. Williams wrote:
> Hans Petter Selasky <> writes:
> > Maybe I am a little too quick to say this, but doesn't the whole USB
> > system just use splnet/splx to protect data structures? On a
> > multiprocessor system, isn't things going to crash after a while, hence
> > more than one CPU can enter into the code that is protected by
> > splnet/splx ? So actually it is time they implement mutexes in NetBSD
> > too?
> NetBSD's SMP kernel is under a big-lock, so this isn't a problem for
> the time being.

This almost sounds like the Giant lock on FreeBSD. But then, actually 
splnet/splx and simple_lock/simple_unlock does not have any effect at all?

What happens on NetBSD if a process calls "tsleep()" while holding a 
simple_lock()? Is there any code to do extra checking like on FreeBSD ?

I've heard that NetBSD is very against mutexes. Is this true? Will NetBSD 
always use one lock for the whole kernel?