From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 95EE6C47423 for ; Fri, 2 Oct 2020 12:54:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 50FA820719 for ; Fri, 2 Oct 2020 12:54:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601643271; bh=/Jvd9G9vUFWXYH5i7FKo0KxfQOgjboDZb1vy3XQqRlk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=G7ySEHXe/+a6/DUje0qELoNNnVpyGN3/XamfqwtIPUh0tWB42uuUc7uIAZc+aXb7O BJyoIbybRylOAeSEymk0/zEJWJ+PlkbdPdtaw0vUzP7xGP9oezqrDC3DIpXZk4KTMz Ilz35s1q+BR7DAT8WSC6x7F24sF5cuupTrqzx3TE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387767AbgJBMya (ORCPT ); Fri, 2 Oct 2020 08:54:30 -0400 Received: from mail.kernel.org ([198.145.29.99]:55356 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726017AbgJBMya (ORCPT ); Fri, 2 Oct 2020 08:54:30 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2F06F206DC; Fri, 2 Oct 2020 12:54:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601643269; bh=/Jvd9G9vUFWXYH5i7FKo0KxfQOgjboDZb1vy3XQqRlk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=VnY1FpYHzs6Ieq/+EBAxAkkAD4q0eS2uCEMO8wYPuxZXlCeYbnXhfCdX6NHDZmy63 n+H0AQyi6jdj/714c0StkOlwRukAxpH/axKD3SL1UULk63tlTRt/2kZPUqv+Tfd9mN O3fnmruZjie9EsvFmkvGtEd2FZMe9Hv2FSxB3Dvw= Date: Fri, 2 Oct 2020 14:54:29 +0200 From: Greg Kroah-Hartman To: Andrzej Pietrasiewicz Cc: linux-kernel@vger.kernel.org, Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Daniel Vetter , Jiri Slaby , Dmitry Torokhov , linux-input@vger.kernel.org, dri-devel@lists.freedesktop.org, kernel@collabora.com Subject: Re: [PATCH v3 2/2] tty/sysrq: Add configurable handler to execute a compound action Message-ID: <20201002125429.GA3350322@kroah.com> References: <20200818112825.6445-1-andrzej.p@collabora.com> <20200818112825.6445-3-andrzej.p@collabora.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200818112825.6445-3-andrzej.p@collabora.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 18, 2020 at 01:28:25PM +0200, Andrzej Pietrasiewicz wrote: > Userland might want to execute e.g. 'w' (show blocked tasks), followed > by 's' (sync), followed by 1000 ms delay and then followed by 'c' (crash) > upon a single magic SysRq. Or one might want to execute the famous "Raising > Elephants Is So Utterly Boring" action. This patch adds a configurable > handler, triggered with 'C', for this exact purpose. The user specifies the > composition of the compound action using syntax similar to getopt, where > each letter corresponds to an individual action and a colon followed by a > number corresponds to a delay of that many milliseconds, e.g.: > > ws:1000c > > or > > r:100eis:1000ub A macro language for sysrq commands, who would have thought... Anyway, _why_ would userland want to do something so crazy as this? What is the use-case here? thanks, greg k-h