From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753886AbcD2PhU (ORCPT ); Fri, 29 Apr 2016 11:37:20 -0400 Received: from mail.kernel.org ([198.145.29.136]:34634 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753230AbcD2PhS (ORCPT ); Fri, 29 Apr 2016 11:37:18 -0400 Date: Fri, 29 Apr 2016 16:37:09 +0100 (BST) From: Stefano Stabellini X-X-Sender: sstabellini@sstabellini-ThinkPad-X260 To: Stefano Stabellini cc: Matt Fleming , Ingo Molnar , Stephen Rothwell , "Luis R. Rodriguez" , Jeremy Fitzhardinge , Konrad Rzeszutek Wilk , Stefano Stabellini , Xen Devel , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Peter Zijlstra , linux-next@vger.kernel.org, linux-kernel@vger.kernel.org, Shannon Zhao , Ard Biesheuvel , Borislav Petkov Subject: Re: efi_enabled(EFI_PARAVIRT) use In-Reply-To: Message-ID: References: <20160429142020.4499e185@canb.auug.org.au> <20160429063936.GA28320@gmail.com> <20160429143931.GG2839@codeblueprint.co.uk> User-Agent: Alpine 2.10 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 29 Apr 2016, Stefano Stabellini wrote: > On Fri, 29 Apr 2016, Matt Fleming wrote: > > On Fri, 29 Apr, at 11:34:45AM, Stefano Stabellini wrote: > > > On Fri, 29 Apr 2016, Ingo Molnar wrote: > > > > Also, it would be nice to have all things EFI in a single tree, the conflicts are > > > > going to be painful! There's very little reason not to carry this kind of commit: > > > > > > > > arch/arm/xen/enlighten.c | 6 +++++ > > > > drivers/firmware/efi/arm-runtime.c | 17 +++++++++----- > > > > drivers/firmware/efi/efi.c | 45 ++++++++++++++++++++++++++++++++------ > > > > 3 files changed, 56 insertions(+), 12 deletions(-) > > > > > > > > in the EFI tree. > > > > > > That's true. I'll drop this commit from xentip and let Matt pick it up > > > or request changes as he sees fit. > > > > One small change I think would be sensible to make is to expand > > EFI_PARAVIRT into a few more bits to clearly indicate the quirks on > > Xen, and in the process, to delete EFI_PARAVIRT. > > > > That should address Ingo's major concern, and also make it much easier > > to rework the code in a piecemeal fashion. > > > > Could somebody enumerate the things that make Xen (dom0) different on > > arm* compared with bare metal EFI boot? The list I made for x86 was, > > > > 1. Has no EFI memory map > > 2. Runtime regions do not need to be mapped > > 3. Cannot call SetVirtualAddressMap() > > 4. /sys/firmware/efi/fw_vendor is invisible > > > > The first maps to not setting EFI_MEMMAP, the second to not setting > > EFI_RUNTIME. If we add EFI_ALREADY_VIRTUAL and EFI_FW_VENDOR_INVISIBLE > > to efi.flags that should cover everything on x86. Does arm* require > > anything else? > > Xen on ARM is different, the impact should be limited: > > - there are no BootServices (ExitBootServices has already been called) > - RuntimeServices go via hypercalls > > The UEFI memory map is still available at an address specified on device > tree like on native, but the compatibility string is different > ("xen,uefi-mmap-start") to clarify that we are booting on Xen rather > than native. > > That's pretty much it, Shannon please confirm. This is to say that Xen on ARM might only need EFI_RUNTIME.