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 Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E4157C433F5 for ; Wed, 18 May 2022 11:08:05 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4L39Fc41Y4z3cCm for ; Wed, 18 May 2022 21:08:04 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=suse.com header.i=@suse.com header.a=rsa-sha256 header.s=susede1 header.b=T0gGp12c; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=suse.com (client-ip=195.135.220.28; helo=smtp-out1.suse.de; envelope-from=pmladek@suse.com; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=suse.com header.i=@suse.com header.a=rsa-sha256 header.s=susede1 header.b=T0gGp12c; dkim-atps=neutral Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4L352n3TzKz3bbQ for ; Wed, 18 May 2022 17:58:24 +1000 (AEST) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id 1B35021B9A; Wed, 18 May 2022 07:58:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1652860701; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=QH8rZRpDaB1rKzYBSvbHTkuJfXIZgq5PPOEyov0S61g=; b=T0gGp12c0pU5b8b1i3GTuIGm3SeP3EhRpXPECQNn/enftlsKdapz4VZkfCcS2uIPqM17q+ /PBA3AVHUNLBKEckN04LlFAw1RfXD18Ad2wMfhhColdg9InPjS0Cl4zZnO5bfZL0Ln9Soj 5NqvLRJqL5BZI+4DmlPHTXzoYIVJS4o= Received: from suse.cz (unknown [10.100.201.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 0683D2C142; Wed, 18 May 2022 07:58:19 +0000 (UTC) Date: Wed, 18 May 2022 09:58:18 +0200 From: Petr Mladek To: "Guilherme G. Piccoli" Subject: Re: [PATCH 19/30] panic: Add the panic hypervisor notifier list Message-ID: References: <20220427224924.592546-1-gpiccoli@igalia.com> <20220427224924.592546-20-gpiccoli@igalia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Mailman-Approved-At: Wed, 18 May 2022 21:06:24 +1000 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Paul Mackerras , Justin Chen , Pavel Machek , Alexander Gordeev , "K. Y. Srinivasan" , Wei Liu , stern@rowland.harvard.edu, xen-devel@lists.xenproject.org, Christian Borntraeger , linux-pm@vger.kernel.org, linux-um@lists.infradead.org, Nicholas Piggin , luto@kernel.org, Mihai Carabas , tglx@linutronix.de, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, senozhatsky@chromium.org, d.hatayama@jp.fujitsu.com, mhiramat@kernel.org, akpm@linux-foundation.org, linux-hyperv@vger.kernel.org, dave.hansen@linux.intel.com, linux-s390@vger.kernel.org, Stephen Hemminger , Vasily Gorbik , vgoyal@redhat.com, Sven Schnelle , Andrea Parri , linux-xtensa@linux-xtensa.org, john.ogness@linutronix.de, Scott Branden , Doug Berger , Markus Mayer , hidehiro.kawai.ez@hitachi.com, linux-arm-kernel@lists.infradead.org, kernel-dev@igalia.com, fabiomirmar@gmail.com, halves@canonical.com, alejandro.j.jimenez@oracle.com, feng.tang@intel.com, zhenwei pi , will@kernel.org, Florian Fainelli , bhe@redhat.com, corbet@lwn.net, Dexuan Cui , Evan Green , bcm-kernel-feedback-list@broadcom.com, Tianyu Lan , keescook@chromium.org, arnd@arndb.de, Haiyang Zhang , rostedt@goodmis.org, rcu@vger.kernel.org, bp@alien8.de, openipmi-developer@lists.sourceforge.net, Thomas Bogendoerfer , linux-parisc@vger.kernel.org, Sebastian Reichel , linux-alpha@vger.kernel.org, Brian Norris , "David S. Miller" , peterz@infradead.org, linux-remoteproc@vger.kernel.org, mikelley@microsoft.com, sparclinux@vger.kernel.org, Lee Jones , Ard Biesheuvel , linux-leds@vger.kernel.org, x86@kernel.org, mingo@redhat.com, dyoung@redhat.com, paulmck@kernel.org, Heiko Carstens , Shile Zhang , Wang ShaoBo , Christophe JAILLET , David Gow , linux-tegra@vger.kernel.org, andriy.shevchenko@linux.intel.com, Hari Bathini , linux-edac@vger.kernel.org, jgross@suse.com, netdev@vger.kernel.org, kernel@gpiccoli.net, kexec@lists.infradead.org, linux-mips@vger.kernel.org, Julius Werner , vkuznets@redhat.com, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Tue 2022-05-17 15:57:34, Petr Mladek wrote: > On Mon 2022-05-16 12:06:17, Guilherme G. Piccoli wrote: > > >> --- a/drivers/soc/bcm/brcmstb/pm/pm-arm.c > > >> +++ b/drivers/soc/bcm/brcmstb/pm/pm-arm.c > > >> @@ -814,7 +814,7 @@ static int brcmstb_pm_probe(struct platform_device *pdev) > > >> goto out; > > >> } > > >> > > >> - atomic_notifier_chain_register(&panic_notifier_list, > > >> + atomic_notifier_chain_register(&panic_hypervisor_list, > > >> &brcmstb_pm_panic_nb); > > > > > > I am not sure about this one. It instruct some HW to preserve DRAM. > > > IMHO, it better fits into pre_reboot category but I do not have > > > strong opinion. > > > > Disagree here, I'm CCing Florian for information. > > > > This notifier preserves RAM so it's *very interesting* if we have > > kmsg_dump() for example, but maybe might be also relevant in case kdump > > kernel is configured to store something in a persistent RAM (then, > > without this notifier, after kdump reboots the system data would be lost). > > I see. It is actually similar problem as with > drivers/firmware/google/gsmi.c. As discussed in the other other reply, it seems that both affected notifiers do not store kernel logs and should stay in the "hypervisor". > I does similar things like kmsg_dump() so it should be called in > the same location (after info notifier list and before kdump). > > A solution might be to put it at these notifiers at the very > end of the "info" list or make extra "dump" notifier list. I just want to point out that the above idea has problems. Notifiers storing kernel log need to be treated as kmsg_dump(). In particular, we would need to know if there are any. We do not need to call "info" notifier list before kdump when there is no kernel log dumper registered. Best Regards, Petr