From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Io3PF-0001mc-4K for qemu-devel@nongnu.org; Fri, 02 Nov 2007 16:46:17 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1Io3PD-0001iy-DR for qemu-devel@nongnu.org; Fri, 02 Nov 2007 16:46:16 -0400 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Io3PD-0001ii-57 for qemu-devel@nongnu.org; Fri, 02 Nov 2007 16:46:15 -0400 Received: from nan.false.org ([208.75.86.248]) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1Io3PC-00006W-Aj for qemu-devel@nongnu.org; Fri, 02 Nov 2007 16:46:14 -0400 Received: from nan.false.org (localhost [127.0.0.1]) by nan.false.org (Postfix) with ESMTP id B65169829E for ; Fri, 2 Nov 2007 20:46:11 +0000 (GMT) Received: from caradoc.them.org (22.svnf5.xdsl.nauticom.net [209.195.183.55]) by nan.false.org (Postfix) with ESMTP id 6DE3698103 for ; Fri, 2 Nov 2007 20:46:11 +0000 (GMT) Received: from drow by caradoc.them.org with local (Exim 4.68) (envelope-from ) id 1Io3P8-0003s1-B0 for qemu-devel@nongnu.org; Fri, 02 Nov 2007 16:46:10 -0400 Date: Fri, 2 Nov 2007 16:46:10 -0400 From: Daniel Jacobowitz Subject: Re: [Qemu-devel] qemu-system-ppc problem with PVR access from user space Message-ID: <20071102204610.GA14306@caradoc.them.org> References: <472B2044.9080601@windriver.com> <1194010730.16781.510.camel@rapid> <472B2CD5.9060209@windriver.com> <1194020639.8327.47.camel@jma4.dev.netgem.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1194020639.8327.47.camel@jma4.dev.netgem.com> Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org On Fri, Nov 02, 2007 at 05:23:59PM +0100, Jocelyn Mayer wrote: > No, it's not accidental. An application accessing priviledged SPR, > including the PVR, is likely to be buggy. I checked in the kernel > (2.6.23), trapping the mfpvr instruction is a huge bug because it breaks > the virtualisation features of the PowerPC architecture. Application > like mol will suffer of this, not being able to pretend the virtualized > CPU is not the same as the host CPU. The PowerPC architecture has been > designed to be fully virtualisable but the vanilla Linux kernel breaks > this useful feature. The bug is then to be fixed in the kernel (and the > glibc if it really uses mfpvr). I suggest you take this up with the PowerPC kernel maintainers, which might work, instead of making QEMU noisy about it; the people using QEMU don't care, and they'll just disable the warning. It wasn't an accidental decision on the kernel maintainers' part either. I don't see the PVR read in current glibc, but I thought it was there; I don't remember exactly what happened. -- Daniel Jacobowitz CodeSourcery