freebsd-questions Digest, Vol 709, Issue 5

Valeri Galtsev galtsev at
Thu Jan 11 15:57:10 UTC 2018

On 01/11/18 06:14, Dave B via freebsd-questions wrote:
> That I suspect depends on how many physical address lines are available
> for it via the memory management system.
> If the PC documentation says 8G is the max', then that is probably all
> that'll be seen by the CPU, even if there is 16G installed.
> There is only one way to find out for sure, at your expense.
> Personally, I doubt it, and the info at
>  says it wont.
> If it does see 16G (or more) best park it in a corner and thrash it with
> a Live Boot Memtest86 CD for some days, to ensure it's working
> correctly.   (Let it run to full completion, it can take hours for a
> full test, even for 4G!)

In addition to memtest86 I would also run much more stressful test, 
namely have the machine booted into system, run multiple CPU and RAM 
hungry stuff (make buildworld comes to my mind). The reason for that 
would be: with signals on memory bus marginally out of specs, system 
stress will help them being pushed to the limit, which "unstressful" 
memtest86 will not do and may pass, though the failure on stressed 
system still may happen.

Just my $0.02


> But even that, doesn’t fully exercise the memory management system in
> the same way an OS will.
> Chances are, if it works at all with the large memory modules, it'll
> only "See" and be able to use 8G.
> Have Fun.
> Dave B.
> On 11/01/18 12:00, freebsd-questions-request at wrote:
>> Subject:
>> OT: Max system physical memory
>> From:
>> Aryeh Friedman <aryeh.friedman at>
>> Date:
>> 10/01/18 14:59
>> To:
>> FreeBSD Mailing List <freebsd-questions at>
>> My computer (HP Pavilion P7-1234, FreeBSD 11.1-RELEASE [amd64]) has 2 240
>> pin DIMM (DDR3, PC3-10600) the manual says the max memory is 8 GB but I see
>> some 16 GB packages (2x8GB).   If I put one or two of these in will it see
>> the extra memory?
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Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247

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