Re: [PATCH] gcc-plugins: simplify GCC plugin-dev capability test

From: Linus Torvalds <torvalds@linux-foundation.org>
To: Jon Hunter <jonathanh@nvidia.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
	Kees Cook <keescook@chromium.org>,
	Emese Revfy <re.emese@gmail.com>,
	linux-hardening@vger.kernel.org,
	Nathan Chancellor <natechancellor@gmail.com>,
	Nick Desaulniers <ndesaulniers@google.com>,
	clang-built-linux <clang-built-linux@googlegroups.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-tegra <linux-tegra@vger.kernel.org>
Subject: Re: [PATCH] gcc-plugins: simplify GCC plugin-dev capability test
Date: Fri, 18 Dec 2020 09:54:45 -0800	[thread overview]
Message-ID: <CAHk-=wjjiYjCp61gdAMpDOsUBU-A2hFFKJoVx5VAC7yV4K6WYg@mail.gmail.com> (raw)
In-Reply-To: <7e691a61-bf4b-0594-8d6d-36d62a5def0b@nvidia.com>

On Fri, Dec 18, 2020 at 7:33 AM Jon Hunter <jonathanh@nvidia.com> wrote:
>
> However, if you are saying that this is a problem/bug with our builders,
> then of course we will have to get this fixed.

This seems to be a package dependency problem with the gcc plugins -
they clearly want libgmp, but apparently the package hasn't specified
that dependency.

If this turns out to be a big problem, I guess we can't simplify the
plugin check after all.

We historically just disabled gcc-plugins if that header didn't build,
which obviously meant that it "worked" for people, but it also means
that clearly the coverage can't have been as good as it could/should
be.

So if it's as simple as just installing the GNU multiprecision
libraries ("gmp-devel" on most rpm-based systems, "libgmp-dev" on most
debian systems), then I think that's the right thing to do. You'll get
a working build again, and equally importantly, your build servers
will actually do a better job of covering the different build options.

                     Linus