Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754913Ab2E2SAU (ORCPT ); Tue, 29 May 2012 14:00:20 -0400 Received: from mga02.intel.com ([134.134.136.20]:33003 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754303Ab2E2SAS convert rfc822-to-8bit (ORCPT ); Tue, 29 May 2012 14:00:18 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.67,352,1309762800"; d="scan'208";a="145883895" From: "Luck, Tony" To: Kees Cook , Anton Vorontsov CC: Greg Kroah-Hartman , Colin Cross , Steven Rostedt , Frederic Weisbecker , Ingo Molnar , Arnd Bergmann , John Stultz , Shuah Khan , "arve@android.com" , Rebecca Schultz Zavin , Jesper Juhl , Randy Dunlap , Stephen Boyd , Thomas Meyer , Andrew Morton , Marco Stornelli , WANG Cong , "linux-kernel@vger.kernel.org" , "devel@driverdev.osuosl.org" , "linaro-kernel@lists.linaro.org" , "patches@linaro.org" , "kernel-team@android.com" Subject: RE: [PATCH 2/5] pstore: Introduce write_buf backend callback Thread-Topic: [PATCH 2/5] pstore: Introduce write_buf backend callback Thread-Index: AQHNO0U5XSurDYwhFEKM6MvB2BU9WZbhbxiA//+idTA= Date: Tue, 29 May 2012 18:00:16 +0000 Message-ID: <3908561D78D1C84285E8C5FCA982C28F192F5FC4@ORSMSX104.amr.corp.intel.com> References: <20120526133412.GA18001@lizard> <1338039549-24498-2-git-send-email-anton.vorontsov@linaro.org> In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.22.254.140] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1151 Lines: 23 > Hrm, I thought the point of having pstore.buf pre-mapped was to allow > Oopses to be able to write directly to it without needing to hit any > additional kernel code. Maybe I'm misunderstanding this change, > though. I'd like to see Tony's opinion on it. Yes - the ERST backend needs to have a bunch of header ugliness (with special UUIDs) at the front of the buffer that is stored to non-volatile storage. So it allocates its own buffer with all that junk, and then passes the address of the plain data portion of the buffer on to the pstore layer. As we add more backends, it might be that this is only applicable to ERST, and so it might make sense to have it copy the data from some other buffer into its specially crafted one. But we should not lose the "no allocations" property ... everything needed should be pre-allocated so we don't have to try to allocate any memory during a panic. -Tony -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/