From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4B7EFC43334 for ; Mon, 25 Jul 2022 12:25:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234890AbiGYMZ1 convert rfc822-to-8bit (ORCPT ); Mon, 25 Jul 2022 08:25:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36496 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231722AbiGYMZY (ORCPT ); Mon, 25 Jul 2022 08:25:24 -0400 Received: from gandalf.ozlabs.org (mail.ozlabs.org [IPv6:2404:9400:2221:ea00::3]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E4402E089 for ; Mon, 25 Jul 2022 05:25:23 -0700 (PDT) Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mail.ozlabs.org (Postfix) with ESMTPSA id 4LrzlP5kY6z4x1V; Mon, 25 Jul 2022 22:25:20 +1000 (AEST) From: Michael Ellerman To: Dan =?utf-8?Q?Hor=C3=A1k?= Cc: amd-gfx@lists.freedesktop.org, Linus Torvalds , Guenter Roeck , linux-kernel@vger.kernel.org, Alex Deucher , linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH] amdgpu: re-enable DCN for ppc64le In-Reply-To: <20220722145453.eb37bd3a99c4b738ed2e26b9@danny.cz> References: <20220722082122.571974-1-dan@danny.cz> <87o7xhcoqh.fsf@mpe.ellerman.id.au> <20220722145453.eb37bd3a99c4b738ed2e26b9@danny.cz> Date: Mon, 25 Jul 2022 22:25:19 +1000 Message-ID: <87pmhtbcr4.fsf@mpe.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dan Horák writes: > On Fri, 22 Jul 2022 22:32:06 +1000 > Michael Ellerman wrote: >> Dan Horák writes: >> > Commit d11219ad53dc disabled the DCN driver for all platforms that >> > define PPC64 due long build issues during "make allmodconfig" using >> > cross-compilation. Cross-compilation defaults to the ppc64_defconfig >> > and thus big-endian toolchain configuration. The ppc64le platform uses a >> > different ABI and doesn't suffer from the build issues. >> >> Unfortunately it's a bit messier than that. >> >> The build error occurs when the compiler is built to use a 64-bit long >> double type. >> >> The ppc64le ABI document says that long double should be 128-bits, but >> there are ppc64le compilers out there that are configured to use 64-bit >> long double, notably the kernel.org crosstool compilers. >> >> So just testing for CPU_LITTLE_ENDIAN means we'll still get build errors >> on those compilers. >> >> But I think we can detect the long double size and key off that. Can you >> test the patch below works for you? >> >> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig >> index 7aa12e88c580..e9f8cd50af99 100644 >> --- a/arch/powerpc/Kconfig >> +++ b/arch/powerpc/Kconfig >> @@ -281,6 +281,9 @@ config PPC >> # Please keep this list sorted alphabetically. >> # >> >> +config PCC_LONG_DOUBLE_128 >> + def_bool $(success,test "$(shell,echo __LONG_DOUBLE_128__ | $(CC) -E -P -)" = 1) > > ^^^ there is a typo s/PCC/PPC/ :-) Oops, renamed it after testing :} > with that fixed, it then defines AMD_DC_DCN on Fedora 36 with > gcc-12.1.1-1.fc36.ppc64le and we should be OK. Thanks. I'll send a proper patch. cheers