From owner-freebsd-hackers Fri Oct 29 2:59:41 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from herring.nlsystems.com (nlsys.demon.co.uk [158.152.125.33]) by hub.freebsd.org (Postfix) with ESMTP id 33FDF14A0B; Fri, 29 Oct 1999 02:59:35 -0700 (PDT) (envelope-from dfr@nlsystems.com) Received: from salmon.nlsystems.com (salmon.nlsystems.com [10.0.0.3]) by herring.nlsystems.com (8.9.3/8.8.8) with ESMTP id LAA76319; Fri, 29 Oct 1999 11:00:07 +0100 (BST) (envelope-from dfr@nlsystems.com) Date: Fri, 29 Oct 1999 11:00:07 +0100 (BST) From: Doug Rabson To: Jason Thorpe Cc: Andrew Gallatin , freebsd-hackers@FreeBSD.ORG, freebsd-alpha@FreeBSD.ORG Subject: Re: ip forwarding broken on alpha In-Reply-To: <199910290456.VAA10430@lestat.nas.nasa.gov> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Thu, 28 Oct 1999, Jason Thorpe wrote: > On Thu, 28 Oct 1999 21:32:51 -0400 (EDT) > Andrew Gallatin wrote: > > > exception_return & skipped the ipl lowering & the check for an ast > > since I don't think you're ever going to need to check for an ast > > after an interrupt. > > Nonsense. ASTs are a key part of process scheduling, and I'd bet that > you run into strange scheduling behaviour if you don't deal with ASTs > after e.g. clock interrupts. Thats correct. The problem is that we are calling the AST with interrupts enabled which allows unbounded interrupt recursion. This is true in NetBSD (at least in version 1.60 of locore.s) as well. The whole idea of ASTs and SWIs is an awful hangover from the VAX; there must be a better way. -- Doug Rabson Mail: dfr@nlsystems.com Nonlinear Systems Ltd. Phone: +44 181 442 9037 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message