Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751538AbdFFR5J (ORCPT ); Tue, 6 Jun 2017 13:57:09 -0400 Received: from mail-pf0-f196.google.com ([209.85.192.196]:33156 "EHLO mail-pf0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751404AbdFFR5H (ORCPT ); Tue, 6 Jun 2017 13:57:07 -0400 Date: Tue, 06 Jun 2017 10:57:06 -0700 (PDT) X-Google-Original-Date: Tue, 06 Jun 2017 10:57:03 PDT (-0700) From: Palmer Dabbelt To: merker@debian.org CC: Arnd Bergmann CC: linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/7] RISC-V: Top-Level Makefile for riscv{32,64} In-Reply-To: <20170606173904.GA3220@excalibur.cnev.de> Message-ID: Mime-Version: 1.0 (MHng) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4355 Lines: 91 On Tue, 06 Jun 2017 10:39:04 PDT (-0700), merker@debian.org wrote: > On Mon, Jun 05, 2017 at 09:56:33PM -0700, Palmer Dabbelt wrote: >> On Mon, 29 May 2017 03:50:47 PDT (-0700), Arnd Bergmann wrote: >> > 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. >> >> OK, I didn't know about COMPAT_UTS_MACHINE. That's a much better solution, >> I'll use that. > > Hello Palmer, > > I suppose the commit: > > https://github.com/riscv/riscv-linux/commit/8c826930d2a19ecd4f1036f10a380dc4fddd0da5 > > aims to address this, but it appears to be incomplete. It lacks > the first fragment of the patch above, i.e. the conversion from > the "uname -m" output (i.e. "riscv{64,32}") to the canonical > arch string (i.e. "riscv"). As a result, a native build (which > normally doesn't explicitly pass ARCH=riscv to make and therefore > relies on the output of "uname -m") would fail. Sorry about that, I dropped the commit. I'm in the middle of bisecting to find a regression, so the patch might now show up for a bit, but it'll be fixed.