Date: Fri, 29 Oct 1999 11:00:07 +0100 (BST) From: Doug Rabson <dfr@nlsystems.com> To: Jason Thorpe <thorpej@nas.nasa.gov> Cc: Andrew Gallatin <gallatin@cs.duke.edu>, freebsd-hackers@FreeBSD.ORG, freebsd-alpha@FreeBSD.ORG Subject: Re: ip forwarding broken on alpha Message-ID: <Pine.BSF.4.10.9910291057410.331-100000@salmon.nlsystems.com> In-Reply-To: <199910290456.VAA10430@lestat.nas.nasa.gov>
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On Thu, 28 Oct 1999, Jason Thorpe wrote: > On Thu, 28 Oct 1999 21:32:51 -0400 (EDT) > Andrew Gallatin <gallatin@cs.duke.edu> 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-alpha" in the body of the message
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