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 X-Spam-Level: X-Spam-Status: No, score=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2DE24C4338F for ; Fri, 30 Jul 2021 21:58:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0B0776024A for ; Fri, 30 Jul 2021 21:58:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231178AbhG3V6s (ORCPT ); Fri, 30 Jul 2021 17:58:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42424 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232982AbhG3V50 (ORCPT ); Fri, 30 Jul 2021 17:57:26 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 406C1C061765 for ; Fri, 30 Jul 2021 14:57:20 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id j9-20020a2581490000b02905897d81c63fso6450642ybm.8 for ; Fri, 30 Jul 2021 14:57:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=YFm85Wduq5y+10ZdlPwZKrCLoXRuDpiE2SUIBEh05mI=; b=U0mvENCWcvRKyRvn2QhOha2v5msMUAgGJd6qWARN8JlVW+SveSBU9AHZzHY30udLTL dI8y2k2L3gKEb44JexJ+BqMr5Yec1/6JguqFBD3HOjiUhVoW3weEYXfUtrCucRvhlVJt vEUh4gDN3mGnHfGk8IIovXQp7Cyey8l3UV2eGc23s2qBtcg1BBUWYn2db+YCaEtLcWT+ 4qQYphnmueeR0vQkQGS0jkiWyz2GS6mEbgEOOap5n3f2FX/5lmDHG7qwbCxTaMF1td4v S1EP0zPv7XZL2zo+MmGcMphWl2vOXBdAiqwMurtYO7Vt0KxOGVIJtQjPFYuF6BTklkgL eu5Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=YFm85Wduq5y+10ZdlPwZKrCLoXRuDpiE2SUIBEh05mI=; b=lZtcWEJhwyzPHeIa3IWlLFiGzeA1aBQnp7GxqOJWjW9s1lIvbaswW1afktzJL7N8Km LCGB3bk3mYlAS5x3/cwFU7vi4JAX0znA6Xog/SGp8BL7Eo3DQir6gq682aWXJNTADfC4 9hXbu8S4nkoaEvuSYA83jzuJt5NuQvwsbZn3be3QrmiMH6kfkMWBz05tw846jvnRQLg1 IWyxT4zNktyP8wnfZQUZtrdbna+RYSbmPw5nURJEGq6FMztOM6kcyEeKxptdkr12BsNS 7mQFveIkT+hdTJcuKFbOw6oNALrFM0PLv+4OGPxxj40HWMo5GewFWU/mNmguEUZiJOst 7Vtg== X-Gm-Message-State: AOAM533eQuZ7OZqSdBxTnocSrmtiTp7+u+8MjgEIsfb8QVYdHnQLbhrf Qpq8bTEXA4e/EZjKbtJ7o9af6bbLFMsrLcsNo4c= X-Google-Smtp-Source: ABdhPJzdLBT8dtfCnaLy3CE11KSU6t4LX4eIvQ8k5CuX6emkmHk9XAUJ1ZA/83lNHoKbhGP4p5mChGd3H//kC7ZmI1g= X-Received: from ndesaulniers1.mtv.corp.google.com ([2620:15c:211:202:ca8b:b433:7c1d:90d]) (user=ndesaulniers job=sendgmr) by 2002:a25:aea0:: with SMTP id b32mr5811780ybj.474.1627682239441; Fri, 30 Jul 2021 14:57:19 -0700 (PDT) Date: Fri, 30 Jul 2021 14:57:08 -0700 In-Reply-To: <20210730215708.276437-1-ndesaulniers@google.com> Message-Id: <20210730215708.276437-4-ndesaulniers@google.com> Mime-Version: 1.0 References: <20210730215708.276437-1-ndesaulniers@google.com> X-Mailer: git-send-email 2.32.0.554.ge1b32706d8-goog Subject: [PATCH v5 3/3] Documentation/llvm: update CROSS_COMPILE inferencing From: Nick Desaulniers To: Masahiro Yamada Cc: Miguel Ojeda , Fangrui Song , Michal Marek , Arnd Bergmann , linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org, clang-built-linux@googlegroups.com, Geert Uytterhoeven , Christoph Hellwig , Linus Torvalds , Nick Desaulniers Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org As noted by Masahiro, document how we can generally infer CROSS_COMPILE (and the more specific details about --target and --prefix) based on ARCH. Suggested-by: Masahiro Yamada Signed-off-by: Nick Desaulniers --- Documentation/kbuild/llvm.rst | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/Documentation/kbuild/llvm.rst b/Documentation/kbuild/llvm.rst index b18401d2ba82..4292f0686316 100644 --- a/Documentation/kbuild/llvm.rst +++ b/Documentation/kbuild/llvm.rst @@ -63,6 +63,23 @@ They can be enabled individually. The full list of the parameters: :: Currently, the integrated assembler is disabled by default. You can pass ``LLVM_IAS=1`` to enable it. +Omitting CROSS_COMPILE +---------------------- + +As explained above, ``CROSS_COMPILE`` is used to set ``--target=``. + +Unless ``LLVM_IAS=1`` is specified, ``CROSS_COMPILE`` is also used to derive +``--prefix=`` to search for the GNU assembler. + +If ``CROSS_COMPILE`` is not specified, the ``--target=`` is inferred +from ``ARCH``. + +That means if you use only LLVM tools, ``CROSS_COMPILE`` becomes unnecessary. + +For example, to cross-compile the arm64 kernel:: + + ARCH=arm64 make LLVM=1 LLVM_IAS=1 + Supported Architectures ----------------------- -- 2.32.0.554.ge1b32706d8-goog