Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751954AbcD3OEV (ORCPT ); Sat, 30 Apr 2016 10:04:21 -0400 Received: from mail-pf0-f180.google.com ([209.85.192.180]:34098 "EHLO mail-pf0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750760AbcD3OET (ORCPT ); Sat, 30 Apr 2016 10:04:19 -0400 Subject: Re: efi_enabled(EFI_PARAVIRT) use To: Stefano Stabellini References: <20160429142020.4499e185@canb.auug.org.au> <20160429063936.GA28320@gmail.com> <20160429143931.GG2839@codeblueprint.co.uk> 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, Ard Biesheuvel , Borislav Petkov From: Shannon Zhao Message-ID: <5724BB53.40202@linaro.org> Date: Sat, 30 Apr 2016 22:04:03 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2328 Lines: 57 On 2016年04月29日 23:37, Stefano Stabellini wrote: > 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. > Yes, it needs EFI_RUNTIME_SERVICES. Thanks, -- Shannon