From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from russell.cc (russell.cc [43.229.61.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id C86631A0014 for ; Fri, 27 Nov 2015 17:17:26 +1100 (AEDT) Message-ID: <1448604913.1291.2.camel@russell.cc> Subject: Re: [PATCH V2] powerpc/powernv: Add a kmsg_dumper that flushes console output on panic From: Russell Currey To: Stewart Smith , linuxppc-dev@lists.ozlabs.org Date: Fri, 27 Nov 2015 17:15:13 +1100 In-Reply-To: References: <1448421962-6174-1-git-send-email-ruscur@russell.cc> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, 2015-11-27 at 16:40 +1100, Stewart Smith wrote: > Russell Currey writes: > > On BMC machines, console output is controlled by the OPAL firmware and is > > only flushed when its pollers are called.  When the kernel is in a panic > > state, it no longer calls these pollers and thus console output does not > > completely flush, causing some output from the panic to be lost. > > > > This patch adds a new kmsg_dumper which gets called at panic time to ensure > > panic output is not lost.  It accomplishes this by calling > > OPAL_CONSOLE_FLUSH > > in the OPAL API, and if that is not available, the pollers are called > > enough > > times to (hopefully) completely flush the buffer. > > You may want to add to commit message that this depends on: > https://patchwork.ozlabs.org/patch/547379/ > It doesn't *depend* on it, it's just preferred.  It still works with older Skiboot versions.  I will mention it in the actual commit message for the next revision, though. > (which I'm about to go review) > > Considering this does address an actual bug, should this go to stable@ ? > > (Same question for the skiboot patch) > Yes, both this patch and the corresponding Skiboot patch should go to stable.