Not seeing 1.8gb of Memory

[cybersmurf]

Ok, so I have an Acer Aspire 5100 and I got it from my sis with 1gb of memory. Went out today and upgraded it to 4gb (total capacity) and after having several failed attempts at startup my laptop finally spun to life and is only registering 2.2gb of memory. Is there something in Linux that limits this?

So my failed startup was the system getting past the loading screen and then freezing with a black screen and the mouse as a bog block and nothing moving.

Any help would be appreciated.

[MikeTbob]

Are you sure this machine supports 4GB of RAM?

[cybersmurf]

AcerPanAm.com/us

Yes I checked that before I upgraded it.

[b2bwild]

So you a single DIMM of 4 GB?

[cybersmurf]

No, I have 2x 2GB SODIMM chips

[MikeTbob]

Does the BIOS see all 4 GB?
Check these threads.
Ubuntu 4GB Ram Limitation and Solution
Feature: High Memory In The Linux Kernel | KernelTrap
PAE kernel seems to be the answer, but I haven't done in-depth study yet either.

[cybersmurf]

Yes, I posted the mem scan on LinuxQuestions.org, and they are telling me the BIOS sees it, but Linux does not, I can post the info here I posted there, wait 1...

Linux version 2.6.27.15-170.2.24.fc10.i686 (mockbuild@x86-5.fedora.phx.redhat.co
m) (gcc version 4.3.2 20081105 (Red Hat 4.3.2-7) (GCC) ) #1 SMP Wed Feb 11 23:58
:12 EST 2009
BIOS-provided physical RAM map:
 BIOS-e820: 0000000000000000 - 000000000009dc00 (usable)
 BIOS-e820: 000000000009dc00 - 00000000000a0000 (reserved)
 BIOS-e820: 00000000000d0000 - 0000000000100000 (reserved)
 BIOS-e820: 0000000000100000 - 000000008fe90000 (usable)
 BIOS-e820: 000000008fe90000 - 000000008fe9a000 (ACPI data)
 BIOS-e820: 000000008fe9a000 - 000000008ff00000 (ACPI NVS)
 BIOS-e820: 000000008ff00000 - 00000000a0000000 (reserved)
 BIOS-e820: 00000000e0000000 - 00000000f0000000 (reserved)
 BIOS-e820: 00000000fec00000 - 00000000fec10000 (reserved)
 BIOS-e820: 00000000fee00000 - 00000000fee01000 (reserved)
 BIOS-e820: 00000000fff80000 - 0000000100000000 (reserved)
 BIOS-e820: 0000000100000000 - 0000000160000000 (usable)
DMI present.
last_pfn = 0x8fe90 max_arch_pfn = 0x100000
x86 PAT enabled: cpu 0, old 0x7040600070406, new 0x7010600070106
kernel direct mapping tables up to 38000000 @ 7000-c000
Using x86 segment limits to approximate NX protection

They told me all this mumbo jumbo is reading right for the BIOS

[MikeTbob]

Heh, it's just mombo jumbo to me too.
Do a little more research on PAE kernels.

[cybersmurf]

Fedora 10 memory usage - Page 2 - LinuxQuestions.org

Apparently somebody else was having the same issue. I looked into upgrading my system to x64 and it looked to be a little iffy. I realy don't want to have to do everything over again. I just spent the past 5 days solid tweaking my system out just the way I want it.

[MikeTbob]

I could be mistaken, but you might be able to just install a PAE kernel and be done with it. Keep in mind though, this is just a guess and not first hand knowledge. The PAE kernel is for more than 4GB, I'm not too sure it'll work either. Perhaps you should try a LiveCD such knoppix and see if it has any issues with your RAM.