From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from wf1.mips-uk.com ([194.74.144.154]:44777 "EHLO dl5rb.ham-radio-op.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S937466AbXFHLLs (ORCPT ); Fri, 8 Jun 2007 07:11:48 -0400 Date: Thu, 7 Jun 2007 22:05:12 +0100 From: Ralf Baechle Subject: Re: [RFC PATCH 0/9] Thumb-2 ISA kernel port Message-ID: <20070607210512.GA13729@linux-mips.org> References: <20070606172409.6689.26641.stgit@localhost.localdomain> <20070606182914.GB6303@uranus.ravnborg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070606182914.GB6303@uranus.ravnborg.org> Sender: linux-arch-owner@vger.kernel.org To: Sam Ravnborg Cc: Catalin Marinas , linux-arch@vger.kernel.org, linux-arm-kernel@lists.arm.linux.org.uk List-ID: On Wed, Jun 06, 2007 at 08:29:14PM +0200, Sam Ravnborg wrote: > > Because of the issues listed below, merging the Thumb-2 support into > > the existing arch/arm files would clutter the existing code with > > macros like ARM, THUMB or W (for conditional compilation and the wide > > instruction format). The IT instruction is also not recognised by > > older toolchains and additional (assembler) macros would be needed, > > including support for the inline assembly. I therefore decided to > > create a separate arch/arm_t2 directory that shares a lot of code with > > the existing arch/arm. > > Hi Catalin. > Can you please share with us the strong arguments why another (third) > arm architecture are needed? It's been my experience with 64-bit MIPS that starting off with a 2nd arch then eventually factoring out the differences and unifying things back into a single mips architecture was actually the easier road to go. Downside: this approach takes long term careful coding. It is hell with the kind of "code once and resuse never" style that's only too common in the embedded industry. Ralf