On Wed, 2008-10-01 at 08:54 -0400, Linuxguy123 wrote: > I have a new HP hdx laptop with a Core Duo T8100 processor and 4 GB of > RAM. > > $ uname -a > Linux localhost.localdomain 2.6.26.3-14.fc8 #1 SMP Wed Sep 3 03:40:05 > EDT 2008 i686 i686 i386 GNU/Linux > > Even though I have 4GB of RAM installed, Linux appears to only be using > 3GB of it. > > $ free -t > total used free shared buffers > cached > Mem: 3106944 777056 2329888 0 60608 > 419608 > -/+ buffers/cache: 296840 2810104 > Swap: 2040244 0 2040244 > Total: 5147188 777056 4370132 > > I've read in other posts to this group that the cause of this is that > the BIOS remaps the some (1GB) of memory to serve as address space for > PCI devices, thus creating a memory "hole". > > I understand that some BIOSes allow one to remap those devices elsewhere > in the map. My BIOS does NOT allow that option. > > Questions: > > a) On machines that do not allow PCI remapping, is the processor > physically disallowed from accessing that 4GB of RAM ? Ie have the > address lines from the processor been disconnected from that RAM due to > being connected to the PCI devices ? > > b) How do XP and Vista handle this ? Are they limited to 3GB of RAM > too ? > > c) I am running the 32 bit version of Linux. Would it make any > difference to my RAM access if I ran the 64 bit version ? Overall, the issue is that you are running a 32-bit version of Linux. In order to take advantage of the entire 4GB you need to either: 1) Run a 64-bit version 2) Run the 32-bit PAE kernel (PAE stands for Physical Address Extensions) At this point, it's preferable (IMHO) to just run the 64-bit version if you can stand to re-install. You will get better results overall in terms of performance compared to the PAE kernel and most all of the issues around 32-bit / 64-bit compatibility have been resolved or worked around. See the F9 release notes for details on these. ...and yes, this also applies to Windows systems. You have to run 64-bit versions of Windows XP or Vista to see the full 4GB as well. Cheers, Chris -- ================================== By all means marry; If you get a good wife, you'll be happy. If you get a bad one, you'll become a philosopher. --Socrates -- fedora-list mailing list fedora-list@xxxxxxxxxx To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list Guidelines: http://fedoraproject.org/wiki/Communicate/MailingListGuidelines
