From mboxrd@z Thu Jan 1 00:00:00 1970 From: Linus Torvalds Subject: Re: [git pull] Input updates for 2.6.34-rc6 Date: Fri, 14 May 2010 07:54:53 -0700 (PDT) Message-ID: References: <20100513075728.GF30110@core.coreip.homeip.net> <20100513160117.GB22238@core.coreip.homeip.net> <20100513171639.GA23708@core.coreip.homeip.net> <20100513181002.GB23708@core.coreip.homeip.net> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Return-path: Received: from smtp1.linux-foundation.org ([140.211.169.13]:37316 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751374Ab0ENO5j (ORCPT ); Fri, 14 May 2010 10:57:39 -0400 In-Reply-To: Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: "Eric W. Biederman" Cc: Dmitry Torokhov , Andrew Morton , Linux Kernel Mailing List , linux-input@vger.kernel.org, Bastien Nocera On Fri, 14 May 2010, Eric W. Biederman wrote: > > efi_enabled is a guard on efi calls. If it is true it tells you that > you can make runtime efi calls. If it is false you can't use runtime > efi calls. efi_enabled does not tell you about the presence of efi > on a system. We don't really want to know about the "presense". What we want to know about is whether we were _loaded_ with EFI or not. IOW, even if the system is EFI-capable, if we actually booted through the legacy BIOS interfaces, we would consider ourselves in "legacy" mode. > All of which means in the normal case pay attention to acpi. That is > more likely to be correct and usable than EFI anything. Oh yes. ACPI is actually _tested_, so while it's buggy, it's unlikely to be quite as spectacularly buggy as any EFI interfaces probably are. But the issue here is that on a "legacy PC", we can't just say "ACPI doesn't mention this device, so it can't exist". Because in a legacy PC model, that simply isn't true. All those motherboard devices can easily exist (and do!) even if ACPI/PnP don't mention them. But if we live in a non-legacy world (ie we were loaded through EFI), I think it's much more reasonable to say "we'll ignore any devices not mentioned by ACPI". Linus