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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 78DD6C433F5 for ; Tue, 5 Oct 2021 20:03:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4BE636120A for ; Tue, 5 Oct 2021 20:03:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235134AbhJEUF1 (ORCPT ); Tue, 5 Oct 2021 16:05:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39180 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235467AbhJEUF1 (ORCPT ); Tue, 5 Oct 2021 16:05:27 -0400 Received: from mail-vs1-xe36.google.com (mail-vs1-xe36.google.com [IPv6:2607:f8b0:4864:20::e36]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B475DC061749 for ; Tue, 5 Oct 2021 13:03:35 -0700 (PDT) Received: by mail-vs1-xe36.google.com with SMTP id 188so599540vsv.0 for ; Tue, 05 Oct 2021 13:03:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isovalent-com.20210112.gappssmtp.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=UUkXRCv5i94LaT1bKu68VJnO8Ng6U39KvQpxaI5oMis=; b=VnBAcWCOEFshe2ikd3LGdzGwkowOOOx0e+HQ8J6uZaTfWsDIEdro0peWHE0Mt68rRp 0wl8GYPnPoO9luisuZdXR1csL6ydx/WYsxMaLTkqiedTfTu3x+97p7KpTnr/mBBd/k/x GRy7PmkhnuAGPAG6BnwEUN2ytss3y+xVH4DffHiYq90fc+vavfK4LV6QL8TQsT80wLJn hHvPO2B3tyn1Xvvmp0oGNaTMVWP72xo3w/6bJBLk5InSnjJ5kQbq3q2KGkl56DXuhkmA 0/bybzIOsZ54xdHy8/wSCUAIgQ0mZu5O4iUD7ffJIFX5ETS33kZPEeBYT4eajbfRo4im UbQg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=UUkXRCv5i94LaT1bKu68VJnO8Ng6U39KvQpxaI5oMis=; b=smfdrsgTxrVDo/mvQpwSzubB0v7OlP9XgKOXKOtnNLunPBr+xiEDi+QY79+LABRhwW WwrDGeRJH6N119/CjYAAgvZe11NcTyMi+Y65xUHeE8W6A8I8dinA/q+2bgmXEHeGKgLF mn/RY+mFxHevEkMTptKht40+mXSyGTmBYx/g3noCIchbyk7bkjTNWbZ5FjnAYROP1ZhH oKHLCjxQgyg0UlEEfF3+g4/ynW7CrakiIbI1a/N/ds/B2CpsNnQarHZIli+LWWZsXXkf WYqSrxAG0JwNQ7x8GIY6xJxhfQwfqZnipYfKvy1apnBxfz5eQymchZNAEHPvoXbenEJX ThwQ== X-Gm-Message-State: AOAM531/4/5eQ5zEKgc2JENIYrRUtSbyEkxKjjIqiAS3qgRniu9cz+HV DwUQFE1XfbJHuoMTR0zlNOmz9fNNhr6DgoyduOF66w== X-Google-Smtp-Source: ABdhPJxlirsRB/ttYrKnjt0r3awHnCZi40aESR/AROiJYpZ3iDs8iGF5jLAaoOAUVK7YouqYF0TlJYvj/JQn8+lUuDM= X-Received: by 2002:a67:d08f:: with SMTP id s15mr21422546vsi.54.1633464214840; Tue, 05 Oct 2021 13:03:34 -0700 (PDT) MIME-Version: 1.0 References: <20211001110856.14730-1-quentin@isovalent.com> <20211001110856.14730-7-quentin@isovalent.com> In-Reply-To: From: Quentin Monnet Date: Tue, 5 Oct 2021 21:03:23 +0100 Message-ID: Subject: Re: [PATCH bpf-next v2 6/9] bpf: iterators: install libbpf headers when building To: Andrii Nakryiko Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Networking , bpf Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Mon, 4 Oct 2021 at 22:30, Quentin Monnet wrote: > > On Mon, 4 Oct 2021 at 20:11, Andrii Nakryiko wrote: > > > > On Sat, Oct 2, 2021 at 3:12 PM Quentin Monnet wrote: > > > > > > On Sat, 2 Oct 2021 at 21:27, Quentin Monnet wrote: > > > > > > > > On Sat, 2 Oct 2021 at 00:20, Andrii Nakryiko wrote: > > > > > > > > > > On Fri, Oct 1, 2021 at 4:09 AM Quentin Monnet wrote: > > > > > > > > > > > > API headers from libbpf should not be accessed directly from the > > > > > > library's source directory. Instead, they should be exported with "make > > > > > > install_headers". Let's make sure that bpf/preload/iterators/Makefile > > > > > > installs the headers properly when building. > > > > > > > > > > > > > > > > -$(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(OUTPUT) > > > > > > +$(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) \ > > > > > > + | $(LIBBPF_OUTPUT) $(LIBBPF_INCLUDE) > > > > > > > > > > Would it make sense for libbpf's Makefile to create include and output > > > > > directories on its own? We wouldn't need to have these order-only > > > > > dependencies everywhere, right? > > > > > > > > Good point, I'll have a look at it. > > > > Quentin > > > > > > So libbpf already creates the include (and parent $(DESTDIR)) > > > directory, so I can get rid of the related dependencies. But I don't > > > see an easy solution for the output directory for the object files. > > > The issue is that libbpf's Makefile includes > > > tools/scripts/Makefile.include, which checks $(OUTPUT) and errors out > > > > Did you check what benefits the use of tools/scripts/Makefile.include > > brings? Last time I had to deal with some non-trivial Makefile > > problem, this extra dance with tools/scripts/Makefile.include and some > > related complexities didn't seem very justified. So unless there are > > some very big benefits to having tool's Makefile.include included, I'd > > rather simplify libbpf's in-kernel Makefile and make it more > > straightforward. We have a completely independent separate Makefile > > for libbpf in Github, and I think it's more straightforward. Doesn't > > have to be done in this change, of course, but I was curious to hear > > your thoughts given you seem to have spent tons of time on this > > already. > > No, I haven't checked in details so far. I remember that several > elements defined in the Makefile.include are used in libbpf's > Makefile, and I stopped at that, because I thought that a refactoring > of the latter would be beyond the current set. But yes, I can have a > look at it and see if it's worth changing in a follow-up. Looking more at tools/scripts/Makefile.include: It's 160-line long and does not include any other Makefile, so there's nothing in it that we couldn't re-implement in libbpf's Makefile if necessary. This being said, it has a number of items that, I think, are good to keep there and share with the other tools. For example: - The $(EXTRA_WARNINGS) definitions - QUIET_GEN, QUIET_LINK, QUIET_CLEAN, which are not mandatory to have but integrate nicely with the way other tools (or kernel components) are built - Some overwrites for the toolchain, if $(LLVM) or $(CROSS_COMPILE) are set Thinking more about this, if we want to create the $(OUTPUT) directory in libbpf itself, we could maybe just enclose the check on its pre-existence in tools/scripts/Makefile.include with a dedicated variable ("ifneq ($(_skip_output_check),) ...") and set the latter in Makefile.include. This way we wouldn't have to change the current Makefile infra too much, and can keep the include. Quentin