From: Andi Kleen <ak@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Arnd Bergmann <arnd@arndb.de>, Nicolas Pitre <nico@linaro.org>,
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
Date: Mon, 17 Dec 2018 16:08:00 -0800 [thread overview]
Message-ID: <20181218000800.GB25620@tassilo.jf.intel.com> (raw)
In-Reply-To: <20181217225020.GA16520@hirez.programming.kicks-ass.net>
On Mon, Dec 17, 2018 at 11:50:20PM +0100, Peter Zijlstra wrote:
> 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..) ?
Can you actually define what optimization you are worred about?
If there are optimizations that cause problems they likely happen
even without LTO inside files. The only difference with LTO is that it
does them between files too.
-Andi
next prev parent reply other threads:[~2018-12-18 0:08 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-20 21:59 [PATCH 0/7] ARM: hacks for link-time optimization Arnd Bergmann
2018-02-20 21:59 ` [PATCH 1/7] ARM: disallow combining XIP and LTO Arnd Bergmann
2018-02-21 3:01 ` Nicolas Pitre
2018-02-21 11:50 ` Arnd Bergmann
2018-02-21 15:13 ` Nicolas Pitre
2018-03-12 2:40 ` Nicolas Pitre
2018-03-12 13:52 ` Arnd Bergmann
2018-03-12 16:46 ` Arnd Bergmann
2018-03-12 17:00 ` Nicolas Pitre
2018-03-12 17:05 ` Nicolas Pitre
2018-03-12 17:07 ` Arnd Bergmann
2018-02-20 21:59 ` [PATCH 2/7] ARM: LTO: avoid THUMB2_KERNEL+LTO Arnd Bergmann
2018-02-21 3:12 ` Nicolas Pitre
2018-02-21 11:48 ` Arnd Bergmann
2018-03-07 18:30 ` Matthias Kaehlcke
2018-03-07 18:52 ` Nicolas Pitre
2018-02-20 21:59 ` [PATCH 3/7] [HACK] pass endianess flag to LTO linker Arnd Bergmann
2018-02-21 3:15 ` Nicolas Pitre
2018-02-21 9:44 ` Arnd Bergmann
2018-02-21 8:37 ` Ard Biesheuvel
2018-02-21 9:48 ` Arnd Bergmann
2018-02-21 10:09 ` Ard Biesheuvel
2018-02-21 13:00 ` Arnd Bergmann
2018-02-20 21:59 ` [PATCH 4/7] ARM: io-acorn: fix LTO linking without CONFIG_PRINTK Arnd Bergmann
2018-02-20 21:59 ` [PATCH 5/7] ARM: fix __inflate_kernel_data stack warning for LTO Arnd Bergmann
2018-02-21 3:26 ` Nicolas Pitre
2018-02-20 21:59 ` [PATCH 6/7] ARM: mark assembler-referenced symbols as __visible Arnd Bergmann
2018-02-20 21:59 ` [PATCH 7/7] efi: disable LTO for EFI stub Arnd Bergmann
2018-12-17 22:50 ` [PATCH 0/7] ARM: hacks for link-time optimization Peter Zijlstra
2018-12-18 0:08 ` Andi Kleen [this message]
2018-12-18 9:18 ` Peter Zijlstra
2018-12-18 10:00 ` Peter Zijlstra
2018-12-21 14:23 ` Paul E. McKenney
2018-12-21 17:20 ` Andi Kleen
2018-12-21 18:00 ` Paul E. McKenney
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