[mythtv-users] Mythbuntu 32bit - how much RAM can it use?

Jay Ashworth jra at baylink.com
Sun Dec 18 15:02:08 UTC 2011


----- Original Message -----
> From: "Simon Hobson" <linux at thehobsons.co.uk>

> Close. They can access a full 4GB of address space, but some of that
> is taken up with ROMs, memory mapped I/O, video, etc, etc. How much
> is lost depends very much on what's in the machine (especially
> chipset), but it generally restricts you to about 3GB give or take a
> bit. IIRC some Intel chipsets should leave you with about 3.2G or RAM.

Even closer.  :-)

The limit has to do with how much memory is mapped in kernel mode, and how
much in user.

The largest address space available to any single process -- even in PAE/32
mode -- is 4GB, and you have to leave room in that 4GB for both I/O mappings
*and the kernel*.  The bigger your kernel is, the less room you have for 
user processes, even ignoring the I/O mappings and video and such.

But while PAE buys you the ability to have multiple Really Big Processes, it
does *not* let you have Even Bigger Processes.

More than you really wanted to know: http://www.spack.org/wiki/LinuxRamLimits

Cheers,
-- jra
-- 
Jay R. Ashworth                  Baylink                       jra at baylink.com
Designer                     The Things I Think                       RFC 2100
Ashworth & Associates     http://baylink.pitas.com         2000 Land Rover DII
St Petersburg FL USA      http://photo.imageinc.us             +1 727 647 1274


More information about the mythtv-users mailing list