Thanks for the info, Gavin. >I'm not sure if disabling devices in the BIOS might get >you a little more RAM. Reminds me of the days when we tried to get more than 640K! Scott <div> On 1/18/07, Gavin McCullagh <<a href="mailto:gmccullagh@gmail.com">gmccullagh@gmail.com</a>> wrote:<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> Hi, On Thu, 18 Jan 2007, Scott Ledyard wrote: > Can the x86 versions of Ubuntu (or any OS) employ more than 4GB of RAM? Probably not without a custom kernel.  Linux kernels can indeed do this, but I've been told that there is a considerable performance cost in doing so.         <a href="http://kerneltrap.org/node/2450">http://kerneltrap.org/node/2450</a> I've never used the >4GB stuff myself but I believe it can be done.  one would want to have good reason to bother I suspect. > I read with interest how to size an LTSP server and noticed that people have > recommended lots of RAM. But, I've also heard that a 32 bit processor cannot > physically address more than 4GB of memory. True? In practice yes, for most people. Another thing to bear in mind is that if you do put 4GB RAM in a 32-bit machine you probably won't even be able to address the full 4GB.  The PCI devices are apparently mapped into the 4GB address space too.  So, there is less address space available for RAM. For example, this dell poweredge has 4x 1GB ram sticks in it: gavinmc@moodle:~$ cat /proc/meminfo MemTotal:      3370992 kB ... I guess in practice it would make no difference to put 3.5GB of ram in it as it seemingly can't address more than 3.4GB.  The amount used seems to vary from machine to machine, presumably depending on the nature and number of pci devices.  I'm not sure if disabling devices in the BIOS might get you a little more RAM. Gavin -- edubuntu-users mailing list <a href="mailto:edubuntu-users@lists.ubuntu.com">edubuntu-users@lists.ubuntu.com</a> Modify settings or unsubscribe at: <a href="https://lists.ubuntu.com/mailman/listinfo/edubuntu-users"> https://lists.ubuntu.com/mailman/listinfo/edubuntu-users</a> </blockquote></div>