From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Jones Subject: Re: [PATCH] x86, boot: Allow 64bit EFI kernel to be loaded above 4G Date: Wed, 11 Feb 2015 11:29:58 -0500 Message-ID: <20150211162958.GA18062@fenchurch.internal.datastacks.com> References: <1423015400-12629-1-git-send-email-yinghai@kernel.org> <20150209182742.GQ6461@codeblueprint.co.uk> <20150211155524.GC4665@codeblueprint.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Return-path: Content-Disposition: inline In-Reply-To: <20150211155524.GC4665@codeblueprint.co.uk> Sender: linux-doc-owner@vger.kernel.org To: Matt Fleming Cc: Yinghai Lu , Thomas Gleixner , "H. Peter Anvin" , Ingo Molnar , Jonathan Corbet , Kees Cook , Junjie Mao , "linux-doc@vger.kernel.org" , "linux-efi@vger.kernel.org" , Linux Kernel Mailing List , Matthew Garrett List-Id: linux-efi@vger.kernel.org On Wed, Feb 11, 2015 at 03:55:24PM +0000, Matt Fleming wrote: > On Mon, 09 Feb, at 12:23:15PM, Yinghai Lu wrote: > > On Mon, Feb 9, 2015 at 10:27 AM, Matt Fleming wrote: > > > On Tue, 03 Feb, at 06:03:20PM, Yinghai Lu wrote: > > > > > > The first thing that comes to mind is the issues we experienced last > > > year when adding support for loading initrds above 4GB to the EFI boot > > > stub, c.f. commit 47226ad4f4cf ("x86/efi: Only load initrd above 4g on > > > second try"). > > > > > > Are things going to work correctly this time? > > > > That should be addressed the grub2. > > I vaguely remember thinking that the issue was only experienced when > using the EFI_FILE protocol, which grub2 doesn't use. So the grub > developers may be OK, but we should at least give them a heads up. Looks correct to me. > > I was thinking that we may need to add mem_limit command together with > > linuxefi and initrdefi. > > or add linuxefi64/initrdefi64? > > No, we definitely do not want to add any more grub commands. Definitely agree. > > BTW, I tested loading kernel above grub2 on > > virutalbox, qemu/kvm/OVMF, and real servers (ami ...) all work without problem. > > > > wonder if we need have one black list for 64bit UEFI that does not > > support access > > memory above 4G. > > We have been successful, so far, in not introducing these kind of > blacklists. It would be a shame to start now. >>From grub's point of view I'm not sure why we'd care - the pages kernel and initramfs land in are both from the Boot Services allocator, so if the machine doesn't support high addresses, they won't be there. -- Peter