linux-kernel - Re: [PATCH] x86-64: Prevent gcc from optimizing away venosys

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Message-ID: <1972495451.7278.1307136726542.JavaMail.root@zmail05.collab.prod.int.phx2.redhat.com>
Date:	Fri, 3 Jun 2011 17:32:06 -0400 (EDT)
From:	Dave Anderson <anderson@...hat.com>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	linux-kernel@...r.kernel.org, mingo@...e.hu, jstancek@...hat.com
Subject: Re: [PATCH] x86-64: Prevent gcc from optimizing away venosys_1()



----- Original Message -----
> >  	return 0;
> >  }
> >
> > -static long __vsyscall(3) venosys_1(void)
> > +long __vsyscall(3) venosys_1(void)
> 
> Better add a __used too. Otherwise it can be optimized out again
> in some builds e.g. when someone enables gc-sections for the linker.

Considering that all of the vsyscall prototypes have this attribute:

#define __vsyscall(nr) \
                __attribute__ ((unused, __section__(".vsyscall_" #nr))) notrace

How would any of them work?

Dave

> 
> -Andi
> --
> ak@...ux.intel.com -- Speaking for myself only.
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