Message-ID: <3EBC29A5.1050005@techsource.com>
Date: Fri, 09 May 2003 18:20:21 -0400
From: Timothy Miller <miller@techsource.com>
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To: Ulrich Drepper <drepper@redhat.com>
CC: "H. Peter Anvin" <hpa@zytor.com>, linux-kernel@vger.kernel.org
Subject: Re: hammer: MAP_32BIT
References: <3EBB5A44.7070704@redhat.com> <20030509092026.GA11012@averell> <16059.37067.925423.998433@gargle.gargle.HOWL> <20030509113845.GA4586@averell> <b9gr03$42n$1@cesium.transmeta.com> <3EBC0084.4090809@redhat.com> <3EBC15B5.4070604@zytor.com> <3EBC2164.6050605@redhat.com>
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Ulrich Drepper wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
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> 
> H. Peter Anvin wrote:
> 
> 
>>No, it requires 31-bit addresses, and there was a discussion about how
>>some things need 31-bit and some 32-bit addresses.
> 
> 
> That's completely irrelevant to my point.  Whether MAP_32BIT actually
> has a 31 bit limit or not doesn't matter, it's limited as well in the
> possible mmap blocks it can return.
> 
> The only thing I care about is to have a hint and not a fixed
> requirement for mmap().  All your proposals completely ignored this.
> 

If your program is capable of handling an address with more than 32 
bits, what point is there giving a hint?  Either your program can handle 
64-bit pointers or it cannot.  Any program flexible enough to handle 
either size dynamically would expend enough overhead checking that it 
would be worse than if it just made a hard choice.

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