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=-4.0 required=3.0 tests=BAYES_00,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 8E547C43460 for ; Wed, 28 Apr 2021 12:21:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5C7CC613EA for ; Wed, 28 Apr 2021 12:21:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234587AbhD1MW0 (ORCPT ); Wed, 28 Apr 2021 08:22:26 -0400 Received: from mail-oi1-f171.google.com ([209.85.167.171]:39462 "EHLO mail-oi1-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234356AbhD1MWZ (ORCPT ); Wed, 28 Apr 2021 08:22:25 -0400 Received: by mail-oi1-f171.google.com with SMTP id i81so62846338oif.6; Wed, 28 Apr 2021 05:21:40 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=GRxkUo+PRbe+x5wLLv3keLeEPMkJ2hxH1SQXgu1ocjk=; b=Tvfv2ymW+DV6C/paqY38g+8stelqtlDmdpxOFAMTLj9ElU6eUEzjceL6i82YjTlAfb aloQ8n5YkyWdiyGTjJYsJJQc+zMbKT4vHoHp18Ro3EMT8fodkgQeSroGi3lua9adC9aC FnfqCGazJWKqDKNIU/v+GH06YDdHvXGhLxuPbLeOcSHQi4ioUPQsQrbPK5X9xbBGGs0D 9PcS/al0gxmdXFSe1ARIRi7GFsg+dCpBgp/EnacobG33yU/1s81858BifPL/IO1Wgo70 267erXTpmEydZM3V4jgFbkBec7L4j6S4yXjpk2c1IcyeHI3Xt5aE9D8SJLAuBcci5OZg 0ahA== X-Gm-Message-State: AOAM530KlMoJP6byqnL98IN/B+50zvcWT+OjuDMlzKYP/1knvNv5BVFQ nuDrqDAXr5r+6KPIaJdWYfjV9LFIzcV1OBqMo4I= X-Google-Smtp-Source: ABdhPJxOhMz6a0QlMskPlWjNHUPGrH1Vn78FLKH0qxpCwG0EW2c/SIcnZsKBhMYvQD1e2UvBb9Jr9em/bmGCLMLK8jk= X-Received: by 2002:aca:bc89:: with SMTP id m131mr20193642oif.71.1619612500595; Wed, 28 Apr 2021 05:21:40 -0700 (PDT) MIME-Version: 1.0 References: <20210424021631.1972022-1-rajatja@google.com> <20210424021631.1972022-2-rajatja@google.com> <79b994f2476249498797e1784f735fd7@AcuMS.aculab.com> <21c6b5002c5ad36cd7fe0bb849f5eba12a614bca.camel@suse.com> <0601e45130495b152bec04eee4a50e302db4cfd2.camel@suse.com> In-Reply-To: <0601e45130495b152bec04eee4a50e302db4cfd2.camel@suse.com> From: "Rafael J. Wysocki" Date: Wed, 28 Apr 2021 14:21:27 +0200 Message-ID: Subject: Re: [PATCH v2 2/2] pci: Support "removable" attribute for PCI devices To: Oliver Neukum Cc: David Laight , "Rafael J. Wysocki" , Rajat Jain , Greg Kroah-Hartman , Bjorn Helgaas , Alan Stern , Linux Kernel Mailing List , Linux PCI , "open list:ULTRA-WIDEBAND (UWB) SUBSYSTEM:" , Bjorn Helgaas , Rajat Jain , Jesse Barnes , Dmitry Torokhov Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 28, 2021 at 8:57 AM Oliver Neukum wrote: > > Am Dienstag, den 27.04.2021, 12:59 +0000 schrieb David Laight: > > From: Oliver Neukum > > > Sent: 27 April 2021 13:00 > > > > that is true for those options, but not for the style > > > of PCI hotplug which requires you to push a button and wait > > > for the blinking light. > > > > True, I remember some of those PCI hotplug chassis from 25 years ago. > > ISTR we did get the removal events working (SVR4/Unixware) but I > > don't remember the relevant chassis ever being sold. > > In spite of the marketing hype I suspect it was only ever possible > > to remove a completely working board and replace it with an > > exactly equivalent one. > > > > In any case those chassis are not 'surprise removal'. > > > > More modern drivers are less likely to crash (and burn?) when > > a PCI read returns ~0u. > > But I suspect an awful lot really don't handle surprise removal > > very well at all. > > So you are saying that these systems are so rare that it should be > handled as special cases if at all? In principle, in the wake of Thunderbolt every PCI driver handling PCIe devices needs to be able to deal with a device that's gone away without notice, because in principle any PCIe device can be included into a Thunderbolt docking station which may go away as a whole without notice.