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Date:   Mon, 17 Dec 2018 23:50:20 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Arnd Bergmann <arnd@arndb.de>
Cc:     Nicolas Pitre <nico@linaro.org>, Andi Kleen <ak@linux.intel.com>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Paul McKenney <paulmck@linux.vnet.ibm.com>,
        Will Deacon <will.deacon@arm.com>,
        Ingo Molnar <mingo@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 0/7] ARM: hacks for link-time optimization
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On Tue, Feb 20, 2018 at 10:59:47PM +0100, Arnd Bergmann wrote:
> Hi Nico, all,
> 
> I was playing with ARM link-time optimization handling earlier this
> month, and eventually got it to build cleanly with randconfig kernels,
> but ended up with a lot of ugly hacks to actually pull it off.

How are we dealing with the fact that LTO can break RCU in very subtle
and scary ways?

Do we have a compiler guy on board that has given us a compiler switch
that kills that optimization (and thereby guarantees that behaviour for
future compilers etc..) ?

Also see the thread here:

  https://lkml.kernel.org/r/20171116115810.GH9361@arm.com

(and yes, this is a fine example of how lore sucks for reading email)