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 0F849C3DA7A for ; Thu, 5 Jan 2023 23:43:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236112AbjAEXm7 (ORCPT ); Thu, 5 Jan 2023 18:42:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58450 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235888AbjAEXml (ORCPT ); Thu, 5 Jan 2023 18:42:41 -0500 Received: from mail-pf1-x42f.google.com (mail-pf1-x42f.google.com [IPv6:2607:f8b0:4864:20::42f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4F89C6D514 for ; Thu, 5 Jan 2023 15:41:06 -0800 (PST) Received: by mail-pf1-x42f.google.com with SMTP id e21so16943215pfl.1 for ; Thu, 05 Jan 2023 15:41:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=igut5By295ohhbEPdn0DgsM5vVo3aXkJJjZjswdn8UY=; b=qs7RYzkrlMT2Nl3hQIAyrmGqJrH24pdSDWZlzwhTjCY6nATSPnjRz6EfHi3wfuetnN s60wR3yXY1JTF3+3oy0LRNs2OCgvBKmrI8RAuy/+Pz9om7nxUUri4oTIYe33DCI328W1 7ryeq28hbWdZ9/1juDX2pd2fmLoVn8kc1Nm6Mo4clL6dwVGc2jbU3ExkwTEn8R/+5WaM ykrs8HgNXaOE8vMgwYRm8WLtugNefPG006dIHMsyK2sB0yIsckEdT87Q6QpGOyVE+/Cm 6at3ZsZixNLe0txQl5RwwBd5hKe1AE9P3mwZ3oKcyFoU0sCdEjBli4T3/7L2lA/qAmr1 nBxA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=igut5By295ohhbEPdn0DgsM5vVo3aXkJJjZjswdn8UY=; b=ZkX+BaxEZveliCswzE3vvV1SKpOetW9aDYoZTbuB0W1/lop3/WlqS6xta5q5E/47p5 9GKOkXOJ/n4aYK6Y9LQ816FIcKyErNaCJjh71ZAjMnJFJovzJL9IZdiFaFnl0LCAFAc8 ewPP1PDuEb54VTkPeP5y0ZP5mgJdzTtJtTf6M94gVSkm9otGroTq/c1y2/hP5a23QCWb 7x+Z0FZwLy0qi7yCMeInue9+1obbDMqykD8fg7xyc3wDr2ogP2A1Jx+mXIoYlGpJHewZ Bt1EigH8vY8InCveIjcsBRSApMSEWxfFUbYw9hLg5xNKyvxNncjLszhlDfBduYJaei5B NNqw== X-Gm-Message-State: AFqh2ko3FZxft2c561PyUuLjs1sp0lYUq/pYr3hOawj3AG2Il1xdLL4q J5SaKSNprDRP9/IW4CepETngcKhbB6AeBSDiMJgtkQ== X-Google-Smtp-Source: AMrXdXugDzcPRw8akQUnimNieQGXT5vrbET6KMq++smBmLsoX9gB0xzfMyGylK18zzLyJ6rGdGEZw7/yCqdVpyI1R+I= X-Received: by 2002:a63:5241:0:b0:4a3:9414:d667 with SMTP id s1-20020a635241000000b004a39414d667mr881249pgl.573.1672962053655; Thu, 05 Jan 2023 15:40:53 -0800 (PST) MIME-Version: 1.0 References: <20230105172243.7238-1-mike.leach@linaro.org> In-Reply-To: From: Mike Leach Date: Thu, 5 Jan 2023 23:40:42 +0000 Message-ID: Subject: Re: [PATCH] perf build: Fix build error when NO_LIBBPF=1 To: Ian Rogers Cc: linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, acme@kernel.org, peterz@infradead.org, mingo@redhat.com, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, namhyung@kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Hi, On Thu, 5 Jan 2023 at 19:03, Ian Rogers wrote: > > On Thu, Jan 5, 2023 at 9:22 AM Mike Leach wrote: > > > > Recent updates to perf build result in the following output when cross > > compiling to aarch64, with libelf unavailable, and therefore > > NO_LIBBPF=1 set. > > > > ``` > > $make -C tools/perf > > > > > > > > Makefile.config:428: No libelf found. Disables 'probe' tool, jvmti > > and BPF support in 'perf record'. Please install libelf-dev, > > libelf-devel or elfutils-libelf-devel > > > > > > > > libbpf.c:46:10: fatal error: libelf.h: No such file or directory > > 46 | #include > > | ^~~~~~~~~~ > > compilation terminated. > > > > ./tools/build/Makefile.build:96: recipe for target > > '.tools/perf/libbpf/staticobjs/libbpf.o' failed > > > > ``` > > > > plus one other include error for > > Ouch, apologies for the breakage. You wouldn't happen to have > something like a way with say a docker image to repro the problem? The > make line above is somewhat minimal. > Unfortunately not - I was cross compiling on my main workstation. However, in theory $make -C tools/perf NO_LIBBPF=1 should explicitly exclude the library from the build - which without the fix it does not. > > The issue is that the commit noted below adds libbpf to the prepare: > > target but no longer accounts for the NO_LIBBPF define. Additionally > > changing the include directories means that even if the libbpf target > > build is prevented, bpf headers are missing in other parts of the build. > > > > This patch ensures that in the case of NO_LIBBPF=1, the build target is > > changed to a header only target, and the headers are installed, without > > attempting to build the libbpf.a target. > > > > Applies to perf/core > > > > Fixes: 746bd29e348f ("perf build: Use tools/lib headers from install path") > > Signed-off-by: Mike Leach > > --- > > tools/perf/Makefile.perf | 10 ++++++++++ > > 1 file changed, 10 insertions(+) > > > > diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf > > index 13e7d26e77f0..ee08ecf469f6 100644 > > --- a/tools/perf/Makefile.perf > > +++ b/tools/perf/Makefile.perf > > @@ -305,7 +305,11 @@ else > > endif > > LIBBPF_DESTDIR = $(LIBBPF_OUTPUT) > > LIBBPF_INCLUDE = $(LIBBPF_DESTDIR)/include > > +ifndef NO_LIBBPF > > LIBBPF = $(LIBBPF_OUTPUT)/libbpf.a > > +else > > +LIBBPF = $(LIBBPF_INCLUDE)/bpf/bpf.h > > This seems strange, don't we want to avoid libbpf targets? > This is a header only target - see my continuation comment below.... > > +endif > > CFLAGS += -I$(LIBBPF_OUTPUT)/include > > > > ifneq ($(OUTPUT),) > > @@ -826,10 +830,16 @@ $(LIBAPI)-clean: > > $(call QUIET_CLEAN, libapi) > > $(Q)$(RM) -r -- $(LIBAPI_OUTPUT) > > > > +ifndef NO_LIBBPF > > $(LIBBPF): FORCE | $(LIBBPF_OUTPUT) > > $(Q)$(MAKE) -C $(LIBBPF_DIR) FEATURES_DUMP=$(FEATURE_DUMP_EXPORT) \ > > O= OUTPUT=$(LIBBPF_OUTPUT)/ DESTDIR=$(LIBBPF_DESTDIR) prefix= \ > > $@ install_headers > > +else > > +$(LIBBPF): FORCE | $(LIBBPF_OUTPUT) > > + $(Q)$(MAKE) -C $(LIBBPF_DIR) OUTPUT=$(LIBBPF_OUTPUT)/ \ > > + DESTDIR=$(LIBBPF_DESTDIR) prefix= install_headers > > +endif > > Shouldn't we just be able to conditionalize having $(LIBBPF) as a > dependency for the perf binary? If there is no dependency then the > targets won't be built and we shouldn't need to conditionalize here. > I did try doing just that, but the build process does two things when building libbpf a) builds the library b) installs the bpf headers in the libbpf output location. Now what the original patch - "perf build: Use tools/lib headers from install path" - does is to also change the include paths to the compiler to pick up the headers, removing the line: INC_FLAGS += -I$(srctree)/tools/lib/ from tools/perf/Makefile.config and adding the line CFLAGS += -I$(LIBBPF_OUTPUT)/include in tools/perf/Makefile.perf (along with similar lines for libperf, libapi etc) The result of this is that if you only remove the library build, the headers are not installed and other compilation units fail as the headers are still included even if the library is not in use. These were originally satisfied by the now removed INC_FLAGS += -I$(srctree)/tools/lib. Thus when NO_LIBBPF=1 even though we do not build the library - we still need to install the headers to retain the consistency - hence a "header only" target, that only installs the headers without building the library. This avoids restoring the original -I$(srctree)/tools/lib/, which would potentially mess up the oher library builds that have changed their header include paths. Regards Mike > Thanks! > Ian > > > $(LIBBPF)-clean: > > $(call QUIET_CLEAN, libbpf) > > -- > > 2.17.1 > > -- Mike Leach Principal Engineer, ARM Ltd. Manchester Design Centre. UK