From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1753727AbcASMYF (ORCPT <rfc822;w@1wt.eu>);
	Tue, 19 Jan 2016 07:24:05 -0500
Received: from smtp.citrix.com ([66.165.176.89]:18613 "EHLO SMTP.CITRIX.COM"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1752116AbcASMXy (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Tue, 19 Jan 2016 07:23:54 -0500
X-IronPort-AV: E=Sophos;i="5.22,317,1449532800"; 
   d="scan'208";a="326104741"
Date: Tue, 19 Jan 2016 12:23:17 +0000
From: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
X-X-Sender: sstabellini@kaball.uk.xensource.com
To: Mark Rutland <mark.rutland@arm.com>
CC: Shannon Zhao <zhaoshenglong@huawei.com>,
        Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
        <ard.biesheuvel@linaro.org>, <leif.lindholm@linaro.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <stefano.stabellini@citrix.com>, <david.vrabel@citrix.com>,
        <catalin.marinas@arm.com>, <will.deacon@arm.com>,
        <julien.grall@citrix.com>, <xen-devel@lists.xen.org>,
        <devicetree@vger.kernel.org>, <linux-efi@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <shannon.zhao@linaro.org>,
        <peter.huangpeng@huawei.com>, Jan Beulich <JBeulich@novell.com>,
        Ian Campbell <Ian.Campbell@citrix.com>
Subject: Re: [PATCH v2 12/16] ARM: Xen: Document UEFI support on Xen ARM
 virtual platforms
In-Reply-To: <20160119104747.GB25024@leverpostej>
Message-ID: <alpine.DEB.2.02.1601191217190.9400@kaball.uk.xensource.com>
References: <1452840929-19612-1-git-send-email-zhaoshenglong@huawei.com>
 <1452840929-19612-13-git-send-email-zhaoshenglong@huawei.com>
 <20160118105115.GD21067@leverpostej>
 <alpine.DEB.2.02.1601181710270.9400@kaball.uk.xensource.com>
 <569E0F15.8090001@huawei.com> <20160119104747.GB25024@leverpostej>
User-Agent: Alpine 2.02 (DEB 1266 2009-07-14)
MIME-Version: 1.0
Content-Type: text/plain; charset="US-ASCII"
X-DLP: MIA1
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Tue, 19 Jan 2016, Mark Rutland wrote:
> On Tue, Jan 19, 2016 at 06:25:25PM +0800, Shannon Zhao wrote:
> > >> We don't do this in Documentation/arm/uefi.txt, and I don't see why we
> > >> should do so here.
> > >>
> > >> Does Xen handle arbitrary size memory map descriptors? I'm not sure what
> > >> new information might be passed in future additions to the descriptor
> > >> format, and I'm not sure what should happen in the Dom0 case.
> > > 
> > > Xen passes to Dom0 the memory map in the same format as the native
> > > memory map.
> 
> Does Xen parse or modify the EFI memory map in any way?

Xen:
- calls EFI_BOOT_SERVICES.GetMemoryMap()
- takes note of the memory regions for its own usage
- create the fdt notes, including efi-mmap-start, with a pointer to it


> Does it pass the raw values returned by EFI_BOOT_SERVICES.GetMemoryMap()
> through to the xen,uefi-* properties, or does is make any static
> assumptions about what the values will be?

It just passes the raw values.


> I'm trying to get a feeling for what the behaviour will be if/when a
> version of the EFI spec expands the memory map format.

Linux is likely to get the memory map in the same format as it's
provided on native.