From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262205AbUEFNX0 (ORCPT ); Thu, 6 May 2004 09:23:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262170AbUEFNVe (ORCPT ); Thu, 6 May 2004 09:21:34 -0400 Received: from atlrel9.hp.com ([156.153.255.214]:44929 "EHLO atlrel9.hp.com") by vger.kernel.org with ESMTP id S262176AbUEFNUR (ORCPT ); Thu, 6 May 2004 09:20:17 -0400 From: "Sourav Sen" To: "'Matt Domsch'" , "'Sourav Sen'" Cc: , , , Subject: RE: [2.6.6 PATCH] Exposing EFI memory map Date: Thu, 6 May 2004 18:50:07 +0530 Message-ID: <004801c4336c$daae5840$39624c0f@india.hp.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook CWS, Build 9.0.2416 (9.0.2911.0) Importance: Normal In-Reply-To: <20040506124649.GA13482@lists.us.dell.com> X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4910.0300 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi Matt, + -----Original Message----- + From: Matt Domsch [mailto:Matt_Domsch@dell.com] + On Thu, May 06, 2004 at 02:22:46PM +0530, Sourav Sen wrote: + > The following simple patch creates a read-only file + > "memmap" under /firmware/efi/ in sysfs + > and exposes the efi memory map thru it. + + I'm not generally opposed, but have a couple questions. + + 1) Why does userspace / humans need to know this? For + debugging firmware? Maybe. But the point I had in mind is, say for example memory diagnostics applications/exercisers which reads (Blind reads, without caring about contents) memory to uncover errors (single bit errors) can use this to know the usable ranges and map them thru /dev/mem and read those ranges. + + 2) Can the memory map output ever be larger than PAGE_SIZE (lower + limit is 4KB on x86)? If not, what guarantees that? If so, you need + your own read mechanism rather than the generic sysfs one. + I don't have an answer right now. I'll investigate. Tony Luck also expressed similar concerns and suggested seq*() interfaces. I'll see how I can do that. + The one-value-per-file rule has an exception for an array of values of + the same type per Documentation/filesystems/sysfs.txt, which this + looks to adhere to. + + Thanks, + Matt + + -- + Matt Domsch + Sr. Software Engineer, Lead Engineer + Dell Linux Solutions linux.dell.com & www.dell.com/linux + Linux on Dell mailing lists @ http://lists.us.dell.com + Thanks Sourav