[j-nsp] 32-Bit JunOS on the 64-Bit Routing Engines

[Keegan Holley]

Sent from my iPhone

On Aug 24, 2011, at 9:13 AM, Chris Adams <cmadams at hiwaay.net> wrote:

> Once upon a time, Keegan Holley <keegan.holley at sungard.com> said:
>> Interestingly enough my SE told us this is possible at lease on our Mx480 and MX960 boxes. Our lab boxes are otherwise engaged at the moment so we havent tested. One note regarding general computing though.  The processor can only address 4G (3.8 or so actually) of ram with a 32 bit word size.  So even if you get the re's running the 32 bit code they will only register 4G of the precious 16G.
> 
> Well, that isn't entirely true.  Intel added the Physical Address
> Extension to the Pentium Pro many years ago (and virtually everything
> claiming to be i686 compatible has PAE).  PAE allows the OS kernel to
> address up to 36 bits of RAM (64G), just not all at once.

I've never heard of this actually being used though.  Maybe I'm wrong though.  Most people just modified their code to support 64 bit and stopped there. I also haven't seen any boards RE's or regular Mobo's with 32 bit procs and support for more that the 4G of RAM.

>  In general, a
> given program can still only see 32 bits, unless it does special bank
> switching.
> 
> I don't know about PAE support on FreeBSD or JUNOS, but it does exist in
> all x86 Juniper hardware.

Interesting.

> -- 
> Chris Adams <cmadams at hiwaay.net>
> Systems and Network Administrator - HiWAAY Internet Services
> I don't speak for anybody but myself - that's enough trouble.
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