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=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 E3C53C388F9 for ; Sat, 21 Nov 2020 07:38:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A935C2223F for ; Sat, 21 Nov 2020 07:38:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="FdaQIrPL" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727208AbgKUHiH (ORCPT ); Sat, 21 Nov 2020 02:38:07 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50194 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726983AbgKUHiG (ORCPT ); Sat, 21 Nov 2020 02:38:06 -0500 Received: from mail-yb1-xb44.google.com (mail-yb1-xb44.google.com [IPv6:2607:f8b0:4864:20::b44]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7FA77C0613CF; Fri, 20 Nov 2020 23:38:06 -0800 (PST) Received: by mail-yb1-xb44.google.com with SMTP id g15so10827741ybq.6; Fri, 20 Nov 2020 23:38:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=V0uMqtuZYyit3rkstjKgdpdIgZ+hwCKX+nB+J4vIPM8=; b=FdaQIrPLzHPeHnyS/kXSYoqjT0PKYicSc5gjxbQyk14akh1tVkLPf6nYY8NvyIht37 CfRUoE5ELPs1JpEA+ZRT3arwi3/oIfe1lFreYv09WE0cNi/062yUNXzPtQVqSSISMu26 0K4jz9U6UkS/iBFyzmmr/UnzrjkhtLy4IV/17RKc+8hZ6tTRqIbngn//eniYlaS81Je+ iIR2wh/PjDHX+JRQozK62Uq9U+PnVetgpe1TShQrGYyx6E/hbUhnYY2gEZFCgxaE/ar6 7phwkeAj4F2lO47Xx4bqz5xzyzlIxWLPyDsjENh9nPLf1Tg7Q8qq6AKlGVQ53hrj1EEc wFdw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=V0uMqtuZYyit3rkstjKgdpdIgZ+hwCKX+nB+J4vIPM8=; b=euIPjoWufOf2T1J+YYaEAKVfV3ClHwzM0L3R58qn+U21cyrJdieu8fyvvm6eYFrFhM USMWSnlPDW5FatfLg4vktMwKbNu3s2E7ZOiyACirSDPJaQEc+e5b0nRvievQ+fd6r2dy DDfLVBPHo1nClO9ZH+r4hr0PFN3t8Z7muNAVu57JLXnB4+HDPKlU2O3hSrti4X7R5xSY pFmBlP/DtWROc2pXVcBG8MAj3CNSCBSeT911aG8IKztIKOEavBvsoOlsH0YiXcdAp1iY i5IC/xMjbY+/3868AXymUA2GuZVc3bzHEFayHWMDBJyYbM417tLmhrPyv9J383z6KOrn duJg== X-Gm-Message-State: AOAM530S3VpxdOGX6DQ90PnvLCdPWQuWtFwjEN+ePBkat6ZtlelXf4WE dRnWzOP/nP57LBqui6/FOn/Cd2YdPWASTwtvHuesCvaHD7TAUg== X-Google-Smtp-Source: ABdhPJwZ6CjIPowUxq3oip+ROMaNn/h2brOlLVZlRVexvOQ9kEIeM067fq0dbIhpztB7MrHazoYaAK2/gwVGAzBSWm4= X-Received: by 2002:a25:df82:: with SMTP id w124mr29190011ybg.347.1605944285647; Fri, 20 Nov 2020 23:38:05 -0800 (PST) MIME-Version: 1.0 References: <20201119085022.3606135-1-davidgow@google.com> In-Reply-To: <20201119085022.3606135-1-davidgow@google.com> From: Andrii Nakryiko Date: Fri, 20 Nov 2020 23:37:54 -0800 Message-ID: Subject: Re: [RFC PATCH] bpf: preload: Fix build error when O= is set To: David Gow Cc: Alexei Starovoitov , Daniel Borkmann , =?UTF-8?B?VG9rZSBIw7hpbGFuZC1Kw7hyZ2Vuc2Vu?= , Networking , bpf , open list , Brendan Higgins , Masami Hiramatsu Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 19, 2020 at 12:51 AM David Gow wrote: > > If BPF_PRELOAD is enabled, and an out-of-tree build is requested with > make O=, compilation seems to fail with: > > tools/scripts/Makefile.include:4: *** O=.kunit does not exist. Stop. > make[4]: *** [../kernel/bpf/preload/Makefile:8: kernel/bpf/preload/libbpf.a] Error 2 > make[3]: *** [../scripts/Makefile.build:500: kernel/bpf/preload] Error 2 > make[2]: *** [../scripts/Makefile.build:500: kernel/bpf] Error 2 > make[2]: *** Waiting for unfinished jobs.... > make[1]: *** [.../Makefile:1799: kernel] Error 2 > make[1]: *** Waiting for unfinished jobs.... > make: *** [Makefile:185: __sub-make] Error 2 > > By the looks of things, this is because the (relative path) O= passed on > the command line is being passed to the libbpf Makefile, which then > can't find the directory. Given OUTPUT= is being passed anyway, we can > work around this by explicitly setting an empty O=, which will be > ignored in favour of OUTPUT= in tools/scripts/Makefile.include. Strange, but I can't repro it. I use make O= all the time with no issues. I just tried specifically with a make O=.build, where .build is inside Linux repo, and it still worked fine. See also be40920fbf10 ("tools: Let O= makes handle a relative path with -C option") which was supposed to address such an issue. So I'm wondering what exactly is causing this problem. > > Signed-off-by: David Gow > --- > > Hi all, > > I'm not 100% sure this is the correct fix here -- it seems to work for > me, and makes some sense, but let me know if there's a better way. > > One other thing worth noting is that I've been hitting this with > make allyesconfig on ARCH=um, but there's a comment in the Kconfig > suggesting that, because BPF_PRELOAD depends on !COMPILE_TEST, that > maybe it shouldn't be being built at all. I figured that it was worth > trying to fix this anyway. > > Cheers, > -- David > > > kernel/bpf/preload/Makefile | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/bpf/preload/Makefile b/kernel/bpf/preload/Makefile > index 23ee310b6eb4..39848d296097 100644 > --- a/kernel/bpf/preload/Makefile > +++ b/kernel/bpf/preload/Makefile > @@ -5,7 +5,7 @@ LIBBPF_A = $(obj)/libbpf.a > LIBBPF_OUT = $(abspath $(obj)) > > $(LIBBPF_A): > - $(Q)$(MAKE) -C $(LIBBPF_SRCS) OUTPUT=$(LIBBPF_OUT)/ $(LIBBPF_OUT)/libbpf.a > + $(Q)$(MAKE) -C $(LIBBPF_SRCS) O= OUTPUT=$(LIBBPF_OUT)/ $(LIBBPF_OUT)/libbpf.a > > userccflags += -I $(srctree)/tools/include/ -I $(srctree)/tools/include/uapi \ > -I $(srctree)/tools/lib/ -Wno-unused-result > -- > 2.29.2.454.gaff20da3a2-goog >