From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: [RFC 00/10] xen/arm: Implement the hypercall
 handling in assembly
Date: Tue, 15 Dec 2015 18:33:27 +0000
Message-ID: <56705CF7.8070309@citrix.com>
References: <1450201928-4928-1-git-send-email-julien.grall@citrix.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Return-path: <xen-devel-bounces@lists.xen.org>
Received: from mail6.bemta3.messagelabs.com ([195.245.230.39])
	by lists.xen.org with esmtp (Exim 4.72)
	(envelope-from <prvs=7840b2d26=Andrew.Cooper3@citrix.com>)
	id 1a8uPw-0000Am-Pb
	for xen-devel@lists.xenproject.org; Tue, 15 Dec 2015 18:33:44 +0000
In-Reply-To: <1450201928-4928-1-git-send-email-julien.grall@citrix.com>
List-Unsubscribe: <http://lists.xen.org/cgi-bin/mailman/options/xen-devel>,
	<mailto:xen-devel-request@lists.xen.org?subject=unsubscribe>
List-Post: <mailto:xen-devel@lists.xen.org>
List-Help: <mailto:xen-devel-request@lists.xen.org?subject=help>
List-Subscribe: <http://lists.xen.org/cgi-bin/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xen.org?subject=subscribe>
Sender: xen-devel-bounces@lists.xen.org
Errors-To: xen-devel-bounces@lists.xen.org
To: Julien Grall <julien.grall@citrix.com>, xen-devel@lists.xenproject.org
Cc: ian.campbell@citrix.com, stefano.stabellini@eu.citrix.com
List-Id: xen-devel@lists.xenproject.org

On 15/12/15 17:51, Julien Grall wrote:
> Hi all,
>
> This patch aims is a first attempt to write the hypercall dispatch in assembly
> in order to avoid reloading the hypercall arguments from the stack.

Why?  A couple of stack operations are in the noise, performance wise.

I have half a patch series to do exactly the opposite for x86 PV guests,
as C is far more maintainable than asm.

~Andrew