From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: Building 32-bit xen.efi for 32-bit EFI platforms Date: Mon, 24 Nov 2014 15:09:39 +0000 Message-ID: <54734A33.6040600@citrix.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Zhuan Chen , xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On 24/11/14 14:59, Zhuan Chen wrote: > Hi, > > I am wondering whether it's possible to build 32-bit xen.efi for the > 32-bit EFI platform? One way of building xen.efi I learnt is to make > the binutils configured with the x86_64-pep emulation (according to > the document http://xenbits.xenproject.org/docs/unstable/misc/efi.html). > The resulted xen.efi is 64-bit mode. Is it possible to build xen.efi > as the 32-bit mode? > > The reason for this question is due to my effort of installing Xen on > the Asus Transformer Book T100, which is one of the Bay Trail Atom > (64-bit processors) tablets shipped with 32-bit EFI firmware. This > requires the support of the 32-bit EFI bootloader. Such platforms seem > to become common and Linux kernel from 3.15 also provides the EFI > mixed mode to support 64-bit kernels running from 32-bit EFI firmware. > > Thanks, > Zhuan 32bit Xen support was removed in Xen 4.3, so building a pure 32bit hypervisor is not possible. There is an argument to be made for building a 32bit Xen.efi which is bootable by a 32bit firmware and moves into 64bit mode on boot. There is however no support for this that I am aware of. ~Andrew