From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Tue, 03 Nov 2009 05:25:53 +0100 (CET) Received: from localhost.localdomain ([127.0.0.1]:59173 "EHLO h5.dl5rb.org.uk" rhost-flags-OK-OK-OK-FAIL) by ftp.linux-mips.org with ESMTP id S1491894AbZKCEZs (ORCPT ); Tue, 3 Nov 2009 05:25:48 +0100 Received: from h5.dl5rb.org.uk (localhost.localdomain [127.0.0.1]) by h5.dl5rb.org.uk (8.14.3/8.14.3) with ESMTP id nA34RDqW015257; Tue, 3 Nov 2009 05:27:13 +0100 Received: (from ralf@localhost) by h5.dl5rb.org.uk (8.14.3/8.14.3/Submit) id nA34RCOe015255; Tue, 3 Nov 2009 05:27:12 +0100 Date: Tue, 3 Nov 2009 05:27:12 +0100 From: Ralf Baechle To: David Daney Cc: linux-mips@linux-mips.org Subject: Re: [PATCH] MIPS: Emulate 64-bit FPU on 64-bit CPUs. Message-ID: <20091103042712.GA14423@linux-mips.org> References: <1257190426-29346-1-git-send-email-ddaney@caviumnetworks.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1257190426-29346-1-git-send-email-ddaney@caviumnetworks.com> User-Agent: Mutt/1.5.19 (2009-01-05) Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 24628 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: ralf@linux-mips.org Precedence: bulk X-list: linux-mips On Mon, Nov 02, 2009 at 11:33:46AM -0800, David Daney wrote: > Running a 64-bit kernel on a 64-bit CPU without an FPU would cause the > emulator to run in 32-bit mode. The c0_Status.FR bit is wired to zero > on systems without an FPU, so using that bit to decide how the > emulator behaves doesn't allow for proper emulation on 64-bit FPU-less > processors. > > Instead, we need to select the emulator mode based on the user-space > ABI. Since the thread flag TIF_32BIT_REGS is used to set > c0_Status.FR, we can just use it to decide if the emulator should be > in 32-bit or 64-bit mode. Thanks, applied! Ralf