From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755254Ab1LAPmw (ORCPT ); Thu, 1 Dec 2011 10:42:52 -0500 Received: from moutng.kundenserver.de ([212.227.17.8]:59235 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755187Ab1LAPmu (ORCPT ); Thu, 1 Dec 2011 10:42:50 -0500 From: Arnd Bergmann To: Catalin Marinas Subject: Re: [Android-virt] [Embeddedxen-devel] [Xen-devel] [ANNOUNCE] Xen port to Cortex-A15 / ARMv7 with virt extensions Date: Thu, 1 Dec 2011 15:42:19 +0000 User-Agent: KMail/1.12.2 (Linux/3.2.0-rc1+; KDE/4.3.2; x86_64; ; ) Cc: Ian Campbell , Stefano Stabellini , "xen-devel@lists.xensource.com" , "linaro-dev@lists.linaro.org" , Pawel Moll , "linux-kernel@vger.kernel.org" , "virtualization@lists.linux-foundation.org" , "android-virt@lists.cs.columbia.edu" , "kvm@vger.kernel.org" , "embeddedxen-devel@lists.sourceforge.net" , "linux-arm-kernel@lists.infradead.org" References: <1322735197.31810.191.camel@zakaz.uk.xensource.com> <20111201151043.GG27394@arm.com> In-Reply-To: <20111201151043.GG27394@arm.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201112011542.19377.arnd@arndb.de> X-Provags-ID: V02:K0:Ycdbw+ncFty38WKX6qb8TPkidZ48FAgA7MIw/6DZTG2 GXdjKYlLACwgkS7naCbeV5TR1TrfAH6eld5dEaUUieNUh0YP5P eSUG9qmH2w14JiS+/+Sbh+EJ+uVqREZs6sh0DBisSIU3FKNRyX k5uckZFQPPDDKC5qW2+Zd9BxH48CIdBD1cleue4Di3FkHLDm1S lkeg0EMqjzd79Zcpsi3QyuaAiNvB7HI7OyZye0Tkh+i+Y9fKCk +bSB5D7/i9gYXgrkKQUH4Hy9e4nmyykCpAUuRYAr0rtXgIMz+e b1g/cGwzy56gKDw5cNFCZvl702k8Mqax6eiaWLbWvCa3rAWxJp +cQbDW2VqhoxB2QxAxNM= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 01 December 2011, Catalin Marinas wrote: > Given the way register banking is done on AArch64, issuing an HVC on a > 32-bit guest OS doesn't require translation on a 64-bit hypervisor. We > have a similar implementation at the SVC level (for 32-bit user apps on > a 64-bit kernel), the only modification was where a 32-bit SVC takes a > 64-bit parameter in two separate 32-bit registers, so packing needs to > be done in a syscall wrapper. How do you deal with signed integer arguments passed into SVC or HVC from a caller? If I understand the architecture correctly, the upper halves of the argument register end up zero-padded, while the callee expects sign-extension. Arnd