From: Andi Kleen <ak@suse.de>
Organization: SUSE Linux Products GmbH, Nuernberg, GF: Markus Rex, HRB 16746 (AG Nuernberg)
To: Ingo Molnar <mingo@elte.hu>
Subject: Re: 2.6.25-rc3: 34TB vmalloc total -- overflow in /proc/meminfo?
Date: Thu, 6 Mar 2008 12:30:38 +0100
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Cc: "Rafael J. Wysocki" <rjw@sisk.pl>, Pavel Machek <pavel@ucw.cz>,
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       Thomas Gleixner <tglx@linutronix.de>
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> but the first fundamental limit we'll hit on 64-bit is the 32-bit offset

31bit to be pedantic.

> limit of binaries - this affects kernel modules, the kernel image, etc. 

If that ever happens just -fPIC mode would need to be supported
and a proper PLT for the references between modules and kernel. It would complicate 
the module loader slightly, but not too much.

> We wont hit that anytime soon, but we'll eventually hit it. (user-space 
> will be the first i guess)

I recently submitted a patch to fix the 2GB limit for user space
binaries (missing O_LARGEFILE). I think it made it into .25.

Newer gcc/binutils support the large code model so you could actually
try to generate binaries that big :-) e.g. some of the rtl-to-C compilers
seem to generate huge code so it might be actually useful.

Also of course you can always split the executable into ~2GB shared libraries.

-Andi

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