From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751152AbdE2Kuu (ORCPT ); Mon, 29 May 2017 06:50:50 -0400 Received: from mail-oi0-f66.google.com ([209.85.218.66]:33421 "EHLO mail-oi0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750886AbdE2Kut (ORCPT ); Mon, 29 May 2017 06:50:49 -0400 MIME-Version: 1.0 In-Reply-To: References: From: Arnd Bergmann Date: Mon, 29 May 2017 12:50:47 +0200 X-Google-Sender-Auth: qtAi1RjNTTJZkgJ9wi3djAC2Cy0 Message-ID: Subject: Re: [PATCH 1/7] RISC-V: Top-Level Makefile for riscv{32,64} To: Palmer Dabbelt Cc: Linux Kernel Mailing List , Olof Johansson , albert@sifive.com Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, May 27, 2017 at 2:57 AM, Palmer Dabbelt wrote: > On Tue, 23 May 2017 04:30:50 PDT (-0700), Arnd Bergmann wrote: >> On Tue, May 23, 2017 at 2:41 AM, Palmer Dabbelt wrote: >>> RISC-V has both 32-bit and 64-bit base ISAs, but they are very similar. >>> Like some other platforms, we'd like to share one arch directory between >>> the two of them. >> >> I think we mainly do the others for backwards-compatibility with ancient >> build scripts, and we don't need that here. Instead, you could add one more >> line to the 'SUBARCH:=' statement that interprets the uname output. > > I don't think that does the same thing. The desired effect of this diff is: > > * "uname -m" when running on a RISC-V machine returns either riscv32 or > riscv64, as that's what tools like autoconf expect when trying to find > tuples. > > * I can cross compile for riscv32 and riscv64. That's currently controlled by > a Kconfig setting, but ARCH=riscv32 vs ARCH=riscv64 controlls what defconfig > sets. > > * I can natively compile for riscv32 and riscv64. That uses the same Kconfig > setting, and the same ARCH=riscv32 vs ARCH=riscv64 switch for defconfig. Right, but my point is that a new architecture should not rely on 'ARCH=' to pick the defconfig, we only do that on a couple of architectures for backwards compatibility with old scripts. > Neither of the two Kconfig issues is a big deal, but we de need "uname -m" to > return "riscv64" or "riscv32" not "riscv". I think the only way to do that is > to set SRCARCH, but I'd be happy to change it if there's a better way. I think > if I just do this > > diff --git a/Makefile b/Makefile > index 0606f28..4adc609 100644 > --- a/Makefile > +++ b/Makefile > @@ -232,7 +232,8 @@ SUBARCH := $(shell uname -m | sed -e s/i.86/x86/ -e s/x86_64/x86/ \ > -e s/arm.*/arm/ -e s/sa110/arm/ \ > -e s/s390x/s390/ -e s/parisc64/parisc/ \ > -e s/ppc.*/powerpc/ -e s/mips.*/mips/ \ > - -e s/sh[234].*/sh/ -e s/aarch64.*/arm64/ ) > + -e s/sh[234].*/sh/ -e s/aarch64.*/arm64/ \ > + -e s/riscv.*/riscv/ ) > > # Cross compiling and selecting different set of gcc/bin-utils > # --------------------------------------------------------------------------- > @@ -269,14 +270,6 @@ ifeq ($(ARCH),x86_64) > SRCARCH := x86 > endif > > -# Additional ARCH settings for RISC-V > -ifeq ($(ARCH),riscv32) > - SRCARCH := riscv > -endif > -ifeq ($(ARCH),riscv64) > - SRCARCH := riscv > -endif > - > # Additional ARCH settings for sparc > ifeq ($(ARCH),sparc32) > SRCARCH := sparc > > then I'll end up with "uname -m" as "riscv" -- I haven't tried it, but that's > why we ended up with this diff in the first place. Do you mean the "uname -m" output comes from "${SRCARCH}" at the time of the kernel build? That would be easy enough to change by simply hardcoding it depending on CONFIG_64BIT. Arnd