Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758459Ab3HMSne (ORCPT ); Tue, 13 Aug 2013 14:43:34 -0400 Received: from bedivere.hansenpartnership.com ([66.63.167.143]:58157 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757276Ab3HMSnc (ORCPT ); Tue, 13 Aug 2013 14:43:32 -0400 Message-ID: <1376419410.3467.67.camel@dabdike.int.hansenpartnership.com> Subject: Re: RFC: default CONFIG_EFI_STUB=y From: James Bottomley To: "H. Peter Anvin" Cc: Ingo Molnar , Thomas Gleixner , Linus Torvalds , "linux-efi@vger.kernel.org" , Linux Kernel Mailing List , Matt Fleming Date: Tue, 13 Aug 2013 11:43:30 -0700 In-Reply-To: <520A7B48.3020304@zytor.com> References: <52050985.9070107@zytor.com> <1376062345.2087.16.camel@dabdike.int.hansenpartnership.com> <52050D03.4030805@zytor.com> <520A7B48.3020304@zytor.com> Content-Type: text/plain; charset="ISO-8859-15" X-Mailer: Evolution 3.8.3 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2203 Lines: 49 On Tue, 2013-08-13 at 11:30 -0700, H. Peter Anvin wrote: > On 08/09/2013 08:38 AM, H. Peter Anvin wrote: > > On 08/09/2013 08:32 AM, James Bottomley wrote: > >> On Fri, 2013-08-09 at 08:23 -0700, H. Peter Anvin wrote: > >>> I would like to change the defaults for CONFIG_EFI and CONFIG_EFI_STUB > >>> to y. There is little reason to omit this since EFI now is a > >>> significant percentage of all systems. > >> > >> You didn't actually attach the patch, but I presume this is for 64 bit > >> compiles on x86 only? We still have significant problems getting 64 bit > >> EFI to interact with 32 bit kernels, so I don't believe we should enable > >> CONFIG_EFI globally for all of x86. > >> > > > > Well, it doesn't *solve* the problem with cross-mode, but it should work > > as-is for EFI32->32-bit kernel and EFI64->64-bit kernel. For the > > cross-mode kernels they will simply not do anything. > > > > Either way, nothing bad should come from it. The worst thing that will > > happen is that the kernel says "I don't have any EFI that I recognize." > > > > Cross-mode support will always require a secondary bootloader (since as > > far as I know there is no concept of "fat binaries" for EFI), but Matt > > Fleming is working on genuine cross-mode support for both the boot stub > > and (eventually) run time support. > > > > James, does this address your concerns? You mean for globally enabling CONFIG_EFI on x86? not really for 32 bit, you say above it's pretty much unusable; I'd prefer just to enable it for 64 bit. As you said in your original post "since EFI now is a significant percentage of all systems" but you actually mean EFI64 ... EFI32 is a pretty insignificant percentage of all systems. Can we actually boot a 32 bit kernel on an EFI64 system? The last time I tried on my Secure Boot SDV it wouldn't work; the problem is getting someting in the transfer of control path to boot the processor back to 32 bit mode. James -- 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/