From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: Re: [PATCH 4/5] xen: introduce XEN_GUEST_HANDLE_PARAM Date: Wed, 8 Aug 2012 08:48:40 +0100 Message-ID: <1344412120.11783.4.camel@dagon.hellion.org.uk> References: <1344262325-26598-4-git-send-email-stefano.stabellini@eu.citrix.com> <5020025C0200007800092FEE@nat28.tlf.novell.com> <1344268070.11339.53.camel@zakaz.uk.xensource.com> <502005B2020000780009302B@nat28.tlf.novell.com> <5020D0B90200007800093181@nat28.tlf.novell.com> <50212F6902000078000933E4@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <50212F6902000078000933E4@nat28.tlf.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Jan Beulich Cc: xen-devel , "Tim Deegan (3P)" , Stefano Stabellini List-Id: xen-devel@lists.xenproject.org On Tue, 2012-08-07 at 14:08 +0100, Jan Beulich wrote: > See how > x86-64 just recently got the ILP32 model [aka x32] added for > this very reason.) For userspace only though, with the kernel remaining a full 64-bit kernel. I don't know what direction they eventually took but there was also a contingent in favour of using the 64-bit syscall ABI for x32. I don't think that the wastage at the hypercall interface is going to be significant. Especially once you consider that many of the 32-bit fields actually need to be 64-bit for a compat mode guest any, e.g. MFNs should certainly be 64 bit regardless or else you impose limitations on 32-bit guests which the 64-bit hypervisor doesn't itself have. Ian.