From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kbuild-owner@vger.kernel.org>
Received: from mail-pg1-f194.google.com ([209.85.215.194]:34072 "EHLO
        mail-pg1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1728797AbfFGPcv (ORCPT
        <rfc822;linux-kbuild@vger.kernel.org>);
        Fri, 7 Jun 2019 11:32:51 -0400
Received: by mail-pg1-f194.google.com with SMTP id h2so1366576pgg.1
        for <linux-kbuild@vger.kernel.org>; Fri, 07 Jun 2019 08:32:51 -0700 (PDT)
Date: Fri, 7 Jun 2019 08:32:46 -0700
From: Tom Roeder <tmroeder@google.com>
Subject: Re: [RFC PATCH] kbuild: Add option to generate a Compilation Database
Message-ID: <20190607153246.GB101503@google.com>
References: <20190606203003.112040-1-rrangel@chromium.org>
 <20190606205406.GA120512@google.com>
 <CAKwvOd=RCL3hpHBVukomrRiXKhvJHMxe3HSrtd0MRcCe1B3ZGw@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CAKwvOd=RCL3hpHBVukomrRiXKhvJHMxe3HSrtd0MRcCe1B3ZGw@mail.gmail.com>
Sender: linux-kbuild-owner@vger.kernel.org
List-ID: <linux-kbuild.vger.kernel.org>
To: Nick Desaulniers <ndesaulniers@google.com>
Cc: Raul E Rangel <rrangel@chromium.org>, Masahiro Yamada <yamada.masahiro@socionext.com>, Matthias Kaehlcke <mka@chromium.org>, zwisler@chromium.org, Joe Lawrence <joe.lawrence@redhat.com>, Kees Cook <keescook@chromium.org>, Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>, Petr Mladek <pmladek@suse.com>, LKML <linux-kernel@vger.kernel.org>, Michal Marek <michal.lkml@markovi.net>, Andy Shevchenko <andriy.shevchenko@linux.intel.com>, Changbin Du <changbin.du@intel.com>, Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>, Sri Krishna chowdary <schowdary@nvidia.com>, Matthew Wilcox <willy@infradead.org>, Mikulas Patocka <mpatocka@redhat.com>, Andrew Morton <akpm@linux-foundation.org>

On Thu, Jun 06, 2019 at 04:40:00PM -0700, Nick Desaulniers wrote:
> On Thu, Jun 6, 2019 at 1:54 PM Tom Roeder <tmroeder@google.com> wrote:
> >
> > On Thu, Jun 06, 2019 at 02:30:03PM -0600, Raul E Rangel wrote:
> > > Clang tooling requires a compilation database to figure out the build
> > > options for each file. This enables tools like clang-tidy and
> > > clang-check.
> > >
> > > See https://clang.llvm.org/docs/HowToSetupToolingForLLVM.html for more
> > > information.
> 
> I'm also super happy to see this!
> https://nickdesaulniers.github.io/blog/2017/05/31/running-clang-tidy-on-the-linux-kernel/
> I don't know enough about GNU Make/Kbuild to answer the questions, but
> hopefully Masahiro can help there.
> 
> > I'm glad to see someone adding this to the Makefile directly. I added
> > scripts/gen_compile_commands.py in b302046 (in Dec 2018) when I was
> 
> Heh, cool.  I had a script that basically did this; we recently
> dropped it from the Android trees when doing an audit of out of tree
> patches.
> 
> > working on using clang-check to look for bugs in KVM. That script
> 
> I'm very interested in this work; my summer intern is looking into
> static analyses of the Linux kernel.  Can you maybe reach out to me
> off thread to tell me more about what you found (or didn't)?
> 
> > > Normally cmake is used to generate the compilation database, but the
> > > linux kernel uses make. Another option is using
> > > [BEAR](https://github.com/rizsotto/Bear) which instruments
> > > exec to find clang invocations and generate the database that way.
> 
> It's probably possible to get this to work w/ GCC if the additional
> dependency of bear exists on the host's system (and may reduce the
> number of implementations).  Downside is the additional host
> dependency.
> 
> Sounds like it may also be possible to just run
> scripts/gen_compile_commands.py at build time if this config is
> enabled?

Yes, for scripts/gen_compile_commands.py, you run a build first with
whatever configuration you want, then call the script to produce the
compile_commands.json file.