# RAM on FreeBSD 9.3



## anonyym (Oct 6, 2014)

Hello, I have a VPS with 8GB RAM and 4 cores but it runs on FreeBSD 9.3 32bit so only 3,5GB are in use.How can i make all 8GB RAM to be available? I read something about PAE but I don't know how to do it. Can someone explain me, please?


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## Beastie (Oct 6, 2014)

Use the amd64 version.


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## usdmatt (Oct 6, 2014)

Yes, it may not be the answer you want (as it means reinstalling the OS) but using the 64bit version of FreeBSD is by far your best option. PAE is just a hack really and has many limitations you have to deal with.

Installing 32bit on any 64bit capable hardware (which is pretty much everything from the last 5+ years) is almost always a mistake, especially if it has >4GB of RAM.

There are PAE instructions for 9.2 at the link below, which should be near identical for 9.3. It lists some of the issues you may have to deal with although it's highly possible that drivers or applications you want to use may also have problems. I don't think much gets proper testing with PAE kernels these days - it really is an unadvisable configuration.

viewtopic.php?t=43177


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## SirDice (Oct 7, 2014)

I agree, use the amd64 version and forget about PAE. Applications need to be specifically aware of PAE to be able to use it. And there are very few programs that can deal with PAE.


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## Terry_Kennedy (Oct 7, 2014)

SirDice said:
			
		

> I agree, use the amd64 version and forget about PAE. Applications need to be specifically aware of PAE to be able to use it. And there are very few programs that can deal with PAE.


The only systems that "need" PAE are the (relatively) small number of systems that can't accept 64-bit-capable processors but which do support large amounts of memory (and have > 4 GB installed*). In the server area, those are things like the Socket 603/604 motherboards for older Xeon CPUs.

Such systems are likely too old to be reliable enough for production use (and with the corresponding unavailability of spare parts at a reasonable price), but might have been re-purposed for hobbyist use. PAE has enough limitations that it isn't usually a good choice, even on hobby systems. Fortunately, most of them show up early enough (incompatible drivers, etc.) that people won't have wasted a lot of time trying it.

While I think it is probably too early to remove PAE support, it might be a good idea to add some boot code to check to see if the CPU is actually 64-bit-capable and suggest that the user start over with an amd64 install, and if not 64-bit-capable say something like "PAE has limited support and is not recommended for new installations". These would be similar to the warnings about the WITNESS / INVARIANTS options enabled in debug kernels.

* Note: I know that not all of the 4 GB will be usable, but enabling PAE to get back the 128 KB to 512 KB from the "hole" (assuming the system remaps it above the 4 GB line) isn't worth the added complexity of PAE.


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