4GB memory in a 32-bit system, detecting only 2.9GB
I have a relatively old computer with Fedora 27, Acer Aspire 5610-BL50 with BIOS v3.60 (latests, https://www.acer.com/ac/en/US/content... ). In order to make it work better, I upgraded the memory and I put two DDR2 ram chips with 2GB each, 4GB in total.
However Fedora only detects 2.9GB. I know that perhaps part of the memory is reserved for the video card (which can't be set to zero in the bios), and also since this is a 32-bit, 4GB should be an upper limit.
But still, why I can't use memory above 2.9GB?
Some answers in AskFedora ( https://ask.fedoraproject.org/en/ques... ) suggest video cards can be using the memory, however I doubt it is using a full 1.0GB.
This is approximately what I see in the BIOS (photo), and below a bunch of diagnostics from the graphical interface and the command line. (for example uname returns a PAE kernel).
$ free -m
total used free shared buff/cache available
Mem: 3018 1659 246 457 1112 945
Swap: 8191 146 8045
$ uname -a
Linux aspire 4.14.8-300.fc27.i686+PAE #1 SMP Wed Dec 20 19:31:13 UTC 2017 i686 i686 i386 GNU/Linux
$ sudo lshw -class memory
*-firmware
description: BIOS
vendor: Acer
physical id: 0
version: V3.60
date: 08/12/2008
size: 101KiB
capacity: 960KiB
capabilities: pci pcmcia pnp upgrade shadowing escd cdboot bootselect int5printscreen int9keyboard int17printer int10video acpi usb agp smartbattery biosbootspecification
*-cache
description: L2 cache
physical id: 5
slot: L2 Cache
size: 2MiB
capacity: 2MiB
capabilities: burst internal write-back
configuration: level=2
*-memory
description: System Memory
physical id: a
slot: System board or motherboard
size: 4GiB
*-bank:0
description: SODIMM DDR2 Synchronous
physical id: 0
slot: M1
size: 2GiB <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
width: 32 bits
*-bank:1
description: SODIMM DDR2 Synchronous
physical id: 1
slot: M2
size: 2GiB <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
width: 32 bits
*-memory:0 UNCLAIMED
description: FLASH memory
product: ENE PCI Memory Stick Card Reader Controller
vendor: ENE Technology Inc
physical id: 4.1
bus info: pci@0000:06:04.1
version: 01
width: 32 bits
clock: 33MHz (30.3ns)
capabilities: pm cap_list
configuration: latency=0 maxlatency=4 mingnt=1
resources: memory:f0203000-f020307f
*-memory:1 UNCLAIMED
description: FLASH memory
product: FLASH memory: ENE Technology Inc:
vendor: ENE Technology Inc
physical id: 4.3
bus info: pci@0000:06:04.3
version: 01
width: 32 bits
clock: 33MHz (30.3ns)
capabilities: pm cap_list
configuration: latency=0 maxlatency=4 mingnt=1
resources: memory:f0203800-f020387f
*-memory:2
description: FLASH memory
product: SD/MMC Card Reader Controller
vendor: ENE Technology Inc
physical id: 4.4
bus info: pci@0000:06:04.4
version: 01
width: 32 bits
clock: 33MHz (30.3ns)
capabilities: pm cap_list
configuration: driver=sdhci-pci latency=0 maxlatency=72 mingnt=32
resources: irq:17 memory:f0202000-f02020ff
Probably a limitation of your Intel 945GM chipset and a sloppy bios. Basically the Memory Controller Hub does not remap Apic or PCI Express memory space and bios designers put a limit of 3GB to addressable ram reserving 1GB for i/o, integrated video card, etc.. They could have calculated the least amount of address space needed, instead they put an hard limit of 1GB. I guess you won't get more than 3GB ram...
@fcomida, sloppy hardware seem a likely explanation. Just to be clear, this has nothing to do with a 32bit vs. 64bit OS, right? If I remember correctly I couldn't install 64bit Fedora even if I wanted to.
To answer the 64bits question, it is important to know if the CPU is capable of 64bits instructions. Please show us the relevant output of
lscpu