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Re: f10.x86_64: laptop HP: Problem to see all 4Gb of memory



-------- Original Message --------
Subject: Re: f10.x86_64: laptop HP: Problem to see all 4Gb of memory
From: Linuxguy123 <linuxguy123 gmail com>
To: Community assistance, encouragement, and advice for using Fedora. <fedora-list redhat com>
Date: 12/04/2008 10:15 AM


The reason I ask is that I am questioning the need for the BIOS upgrade.
Case in point... I'm running an HP HDX9494.  HP states it will only
accept 4 GB of RAM.  People have put 8 GB in it and Windows sees all 8
GB.   I know one person that has 8 GB in his laptop.  I could ask him to
run F10 and find out how much F10 sees.

Not all laptops use the same BIOS, chipset, or motherboards. They're all customized per laptop model series. You quoted an Intel-based laptop. The OP is using an AMD-based laptop.

PCI Memory Remap is not something I made up. There's a good Intel document on this if you don't believe me. Just Google for it. [1]

Quick summary: Legacy items (PCI, ISA, etc) are only set to address 4GB of memory. Unless the BIOS is programmed for remapping address space above 4GB an operating system may only see 3GB of memory.

I've run into this issue when I tried putting in 5 GB of memory into a 64-bit computer. Linux (64-bit) and Windows (32-bit) only saw 3gb of memory until I turned on PCI Memory Remap in my BIOS. Linux then saw the full 5GB.

The only disconnect is that my BIOS reported 3GB with remapping off, yet Dario Lesca says his BIOS reports 4GB. It could just be a difference in vendor BIOSes (ASUS versus HP).

[1] http://www.google.com/search?q=pci+memory+remap


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