4G Memory Only Recognised 3.4G

[Joel Bryan Juliano]

On Dec 18, 2007 8:26 AM, Soo-Hyun Choi <s.choi at hackers.org.uk> wrote:
> Hi,
>
> Recently, I have installed 4 x 1GB memory sticks with Ubuntu 7.10, but my
> system only sees it as 3.4GB. Is this a typical phenomenon? Or, how can I
> fix this problem?
>
> Many thanks,
> Soo-Hyun
>

Hi,

PC users still use the old BIOS (contrast to EFI in Macs) that
interface the software and hardware using DMA that is limited to
32-bit address,
the BIOS allocate a memory enough (as far as it knows) for the PCI
devices, thus the 614MB memory hole occurs.

You can try to pass "enable-pae ht=on" on grub, and see what will
happens, or use a 64-bit Ubuntu version.

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