From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754740Ab1K1UPY (ORCPT ); Mon, 28 Nov 2011 15:15:24 -0500 Received: from merlin.infradead.org ([205.233.59.134]:35994 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754010Ab1K1UPX convert rfc822-to-8bit (ORCPT ); Mon, 28 Nov 2011 15:15:23 -0500 Message-ID: <1322511307.2921.173.camel@twins> Subject: Re: [PATCH 4/9] ftrace: Add enable/disable ftrace_ops control interface From: Peter Zijlstra To: Steven Rostedt Cc: Jiri Olsa , fweisbec@gmail.com, mingo@redhat.com, paulus@samba.org, acme@ghostprotocols.net, linux-kernel@vger.kernel.org Date: Mon, 28 Nov 2011 21:15:07 +0100 In-Reply-To: <1322511125.17003.21.camel@frodo> References: <1322417074-5834-1-git-send-email-jolsa@redhat.com> <1322417074-5834-5-git-send-email-jolsa@redhat.com> <1322508398.17003.9.camel@frodo> <1322510552.2921.167.camel@twins> <1322511125.17003.21.camel@frodo> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT X-Mailer: Evolution 3.2.1- Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2011-11-28 at 15:12 -0500, Steven Rostedt wrote: > Actually, from what I've been told, x86 seems to be the only arch that > does crazy things with NMIs. Most the other archs do NMI when the system > is dead. That is, there's no return to normal system processing once an > NMI is hit. Sparc64 implements effective NMIs by playing games with their interrupt priority levels. local_irq_disable() disable the lower 15 (0-14) levels only, and their PMU interrupts at level 15. That generates an effective NMI (interrupt not blocked by local_irq_disable()).