From owner-freebsd-hackers Fri Mar 24 01:39:08 1995 Return-Path: hackers-owner Received: (from majordom@localhost) by freefall.cdrom.com (8.6.10/8.6.6) id BAA25914 for hackers-outgoing; Fri, 24 Mar 1995 01:39:08 -0800 Received: from godzilla.zeta.org.au (godzilla.zeta.org.au [203.2.228.34]) by freefall.cdrom.com (8.6.10/8.6.6) with ESMTP id BAA25881 for ; Fri, 24 Mar 1995 01:38:44 -0800 Received: (from bde@localhost) by godzilla.zeta.org.au (8.6.9/8.6.9) id TAA12296; Fri, 24 Mar 1995 19:35:31 +1000 Date: Fri, 24 Mar 1995 19:35:31 +1000 From: Bruce Evans Message-Id: <199503240935.TAA12296@godzilla.zeta.org.au> To: FreeBSD-hackers@FreeBSD.org, wilko@yedi.iaf.nl Subject: Re: obscure NMI Sender: hackers-owner@FreeBSD.org Precedence: bulk >Any suggestions on: > NMI port 61 a0, port 70 7f, port 461 10 >? >This happens just after the npx probe message is displayed on _every_ >boot (1.1.5). The system board is a Philips P3464 EISA, with 20Mb mem. NMI was used on XTs for reporting FPU exceptions. It is even less suitable for this purpose than the IRQ13 used on AT's, but XTs have even less spare interrupts than AT's and 8086's don't even generate exceptions for illegal opcodes. The npx probe generates an FPU exception. Perhaps the P3464 generates both IRQ13 and NMI for reporting FPU exceptions. This braindamage is required for compatibility but it is usually implemented in software (by jumping from the IRQ13 handler to the NMI handler after dismissing the IRQ13). Bruce