From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: RFC: default CONFIG_EFI_STUB=y Date: Tue, 13 Aug 2013 11:52:04 -0700 Message-ID: <520A8054.1030108@zytor.com> References: <52050985.9070107@zytor.com> <1376062345.2087.16.camel@dabdike.int.hansenpartnership.com> <52050D03.4030805@zytor.com> <520A7B48.3020304@zytor.com> <1376419410.3467.67.camel@dabdike.int.hansenpartnership.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1376419410.3467.67.camel@dabdike.int.hansenpartnership.com> Sender: linux-kernel-owner@vger.kernel.org To: James Bottomley Cc: Ingo Molnar , Thomas Gleixner , Linus Torvalds , "linux-efi@vger.kernel.org" , Linux Kernel Mailing List , Matt Fleming List-Id: linux-efi@vger.kernel.org On 08/13/2013 11:43 AM, James Bottomley wrote: >> 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. For better or worse, there will be more. > 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. We can boot with a bootloader in "skip stub" mode; no runtime services yet. We are working on making it possible to boot via a EFI stub in assisted mode (still needing a bootloader, but with the boot stub in the kernel.) Runtime services will be the last piece, obviously, but even that looks reasonably doable. -hpa