From owner-freebsd-hackers Thu Nov 13 11:08:19 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.7/8.8.7) id LAA08709 for hackers-outgoing; Thu, 13 Nov 1997 11:08:19 -0800 (PST) (envelope-from owner-freebsd-hackers) Received: from smtp04.primenet.com (smtp04.primenet.com [206.165.5.85]) by hub.freebsd.org (8.8.7/8.8.7) with ESMTP id LAA08704 for ; Thu, 13 Nov 1997 11:08:12 -0800 (PST) (envelope-from tlambert@usr08.primenet.com) Received: (from daemon@localhost) by smtp04.primenet.com (8.8.7/8.8.7) id MAA14341; Thu, 13 Nov 1997 12:08:03 -0700 (MST) Received: from usr08.primenet.com(206.165.6.208) via SMTP by smtp04.primenet.com, id smtpd014331; Thu Nov 13 12:07:59 1997 Received: (from tlambert@localhost) by usr08.primenet.com (8.8.5/8.8.5) id MAA28899; Thu, 13 Nov 1997 12:07:58 -0700 (MST) From: Terry Lambert Message-Id: <199711131907.MAA28899@usr08.primenet.com> Subject: Re: BSDI F0 bug workaround implementation To: rminnich@Sarnoff.COM (Ron G. Minnich) Date: Thu, 13 Nov 1997 19:07:58 +0000 (GMT) Cc: freebsd-hackers@FreeBSD.ORG In-Reply-To: from "Ron G. Minnich" at Nov 13, 97 09:31:07 am X-Mailer: ELM [version 2.4 PL23] Content-Type: text Sender: owner-freebsd-hackers@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk > I'm not sure I understand the full implications of the impact of this > hack, although it is worrisome. Judging by what my pentium book says about > the layout of the IDT, it seems like it will increase interrupt latency > for page faults and many maskable interrupts. Can anyone more > knowledgeable than I comment on this? Page fault overhead on freebsd is > pretty high: would a short-cut make sense that does not go through the > full vm system for this? Otherwise page fault overhead may come close to > doubling ... Only the first 7 IDT entries are affected (at least in the Linux workaround), not the whole table. On the minus side, the impact *is* non-zero. Like the FPU bug, since a workaround exists, it's likely to be swept under the software as well. 8-(. Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers.