linux-kernel - Re: Duplicate vsyscall/vdso gettimeofday implementations on x86

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Message-ID: <87ab32wmkv.fsf@basil.nowhere.org>
Date:	Sat, 18 Jul 2009 08:07:44 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	john stultz <johnstul@...ibm.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...x.de>,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: Duplicate vsyscall/vdso gettimeofday implementations on x86_64

john stultz <johnstul@...ibm.com> writes:
>
> Hrmm. Can we deprecate the old method and push glibc to use the new one?

That would break every old 64bit executable. Also not there are programs
who don't use glibc.

Also glibc's way of calling the vDSO is still somewhat inefficient
(although that could be probably fixed)

> If we remove it the vsyscall interface will old glibc's fall-back
> gracefully? 

They would crash gracefully.

I had a couple of different transition plans, but they were all fairly
complicated and had various disadvantages, so in the end nothing got
done and the old code just left in.

-Andi

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