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Date:      Fri, 30 Nov 2012 16:00:44 +0100
From:      Andrea Venturoli <ml@netfence.it>
To:        freebsd-questions@freebsd.org, mueller23@insightbb.com
Subject:   Re: i386 vs amd64
Message-ID:  <50B8CA1C.3080207@netfence.it>
In-Reply-To: <30.96.29719.275C8B05@smtp01.insight.synacor.com>
References:  <30.96.29719.275C8B05@smtp01.insight.synacor.com>

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On 11/30/12 15:40, Thomas Mueller wrote:
>> On Thu, Nov 29, 2012 at 2:57 PM, Bill Tillman <btillman99@yahoo.com> wrote:
>
>>> i386 will not see anything above 4 GB
>
>
>> Actually you *can* give access to >4Gb RAM for your system: PAE allows you
>> to use 36 bits instead of 32 to address your memory (and supported till
>> Pentium Pro) but that is only for OS (32bit apps would see 4Gb only).
>
>> Anyway, I have not seen any troubles with 64bit installations.
>
>> Ilya.
>
> How does the system know what is OS and what is 32-bit apps?

I think this question is badly written.

A kernel supporting PAE can see and use more than 4GB.
However, since apps runs unmodified, a single process cannot break that 
barrier.

So, if you are running a single program that requires that lot of 
memory, PAE is not an option and you will need amd64.

OTOH, if you run several programs which don't singularly require more 
than 3GB of RAM, PAE might be a viable alternative to reinstalling.



> Where would GCC fit in this regard, or Clang for that matter?

I don't really know, but I don't think it could make any difference.



  bye
	av.



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