From: Andi Kleen <ak@linux.intel.com>
To: Kees Cook <kees@outflux.net>
Cc: Randy Dunlap <rdunlap@infradead.org>,
akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
linux-next@vger.kernel.org, sfr@canb.auug.org.au, mhocko@suse.cz
Subject: Re: mmotm 2014-07-02-15-07 uploaded (stack protector)
Date: Wed, 2 Jul 2014 18:00:19 -0700 [thread overview]
Message-ID: <20140703010019.GS19781@tassilo.jf.intel.com> (raw)
In-Reply-To: <20140703005100.GI5412@outflux.net>
> The problem is that if you make kbuild hard-fail when selecting this missing
> compiler option, you can never switch it back because "make menuconfig" will
> refuse to build since the compiler option would be missing. Being silent
> about the missing option (and/or falling back to other options) means that
> you could get two different kernel features selection with the same CONFIG_*
> set, depending on the kernel, which is extremely bad ("I selected
> stack-protector-strong but it built without it?!").
The assumption that every flag in a .config has been consciouscly
selected by a human is a quite dubious one ...
LTO just turns itself off if the toolchain doesn't support it.
> So, the middle ground was to warn about it during the kbuild logic so
> you could find the source of the problem, but ultimately fail the build
> when the compiler doesn't support it so there weren't any silent failure
> modes.
Longer term it would be of course best to move all the cc-options
probing into Kconfig. I bet that would speed up builds too.
-Andi
next prev parent reply other threads:[~2014-07-03 1:00 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-02 22:08 mmotm 2014-07-02-15-07 uploaded akpm
2014-07-02 23:21 ` mmotm 2014-07-02-15-07 uploaded (stack protector) Randy Dunlap
2014-07-03 0:22 ` Andi Kleen
2014-07-03 0:37 ` Randy Dunlap
2014-07-03 0:51 ` Kees Cook
2014-07-03 0:56 ` Andrew Morton
2014-07-03 1:10 ` [PATCH] kbuild: explain stack-protector-strong CONFIG logic Kees Cook
2014-07-03 1:00 ` Andi Kleen [this message]
2014-07-03 1:13 ` mmotm 2014-07-02-15-07 uploaded (stack protector) Kees Cook
2014-07-03 0:57 ` Kees Cook
2014-07-03 1:42 ` Randy Dunlap
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