linux-kernel - Re: [PATCH 2/2] jump label: disable due to compiler bug

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Message-ID: <20101029122230.GA25663@elte.hu>
Date:	Fri, 29 Oct 2010 14:22:30 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Jason Baron <jbaron@...hat.com>,
	David Daney <ddaney@...iumnetworks.com>, rth@...hat.com,
	"H. Peter Anvin" <hpa@...or.com>, mathieu.desnoyers@...ymtl.ca,
	tglx@...utronix.de, andi@...stfloor.org, roland@...hat.com,
	masami.hiramatsu.pt@...achi.com, fweisbec@...il.com,
	avi@...hat.com, davem@...emloft.net, vgoyal@...hat.com,
	sam@...nborg.org, tony@...eyournoodle.com, dsd@...top.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] jump label: disable due to compiler bug


* Steven Rostedt <rostedt@...dmis.org> wrote:

> On Fri, 2010-10-29 at 08:34 +0200, Ingo Molnar wrote:
> > * Jason Baron <jbaron@...hat.com> wrote:
> > 
> > > Thus, I'm going to propose a patch, which makes jump label conditional on x86_64 
> > > for now [...]
> > 
> > No, we dont do 64-bit only features really.
> > 
> > > [...] (adding -maccumulate-outgoing-args to x86 increases the text size, so I'm 
> > > not proposing adding the flag there).
> > 
> > Please make jump labels configurable instead. (dependent on EMBEDDED)
> 
> Do you mean to have it dependent on !EMBEDDED, or perhaps !CC_OPTIMIZE_FOR_SIZE ?

CC_OPTIMIZE_FOR_SIZE dependency probably not. Might even leave out !EMBEDDED, to 
make it generally configurable.

Also, we should make it default off - we need to see whether there are any compiler 
bugs lurking.

> I can see people making a big stink about adding back a gcc option that makes the 
> kernel bigger.

Depends on exactly how much .text we are talking about here. Plus it would be 
default-off.

Thanks,

	Ingo
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