Without PAE the limit is 3GB of RAM, isn't it?

Asked by Yannis Tsop on 2009-06-29

http://packages.ubuntu.com/karmic/linux-image-2.6.30-10-generic-pae

The description says:
Geared toward 32 bit desktop systems with more then 4GB RAM.

I believe the right is:
Geared toward 32 bit desktop systems with more *than 3GB* RAM.

Question information

Tom (tom6) said : #1

Heck, i've lost my link but i'm pretty sure that 4Gb is right. If someone quoted 3Gb at you then it was probably to ensure room for error, perhaps a laptop issue as they often cream some off for their graphics card? I think you can still use the Pae with less than 4Gb but it'd just be a bit pointless?

Tom (tom6) said : #2

It's better to install stuff through a package manager rather than as individual packages. Synaptic is pretty handy

System - Administration - Synaptic

i would guess you already know that and have good reason to try another way. Anyway, thanks for pointing out a possible error but i am pretty sure it's right :)

Thanks and regards from
Tom :)

32 bits can address 4GB memory. If all of it is available to the operating system will depend on the hardware (See: http://blogs.msdn.com/hiltonl/archive/2007/04/13/the-3gb-not-4gb-ram-problem.aspx where it talks about reasons 32 bit Windows shows less than 4GB)

The PAE wikipedia page pretty much explains what PAE does:

[With PAE] the x86 processor hardware is augmented with additional address lines used to select the additional memory, so physical address size is increased from 32 bits to 36 bits. This increases maximum physical memory size from 4 GB to 64 GB.

Yannis Tsop (ogiannhs) said : #4

I have tried both Windows and Linux with 4GB of RAM and they can only manage 3GB of RAM (or maybe 3.2GB). It is reported as the total amount of memory, so there must be something there.

http://www.dansdata.com/askdan00015.htm
http://community.livejournal.com/linux/1754389.html

Tom (tom6) said : #5

Hi :)

There's 2 side issues worth noting here.

1. Linux seldom needs even as much as 2Gb ram. I've got 2Gb and even with full HDTV multimedia and lots webpages open with quite a few playing multimedia while playing a game i still find it tough to push usage up beyond about 1.5Gb. Windows is very inefficient with system resources but linux is much more intelligent - even the swap-space is is handled better.

2. It's likely to be your graphics card taking off some of the ram because it doesn't have it's own ram onboard. If you want to use a monitor then you're best off not changing this. Look in the bios for clues about how much ram your graphics card has siphoned off.

Oh there's a great tool called "conky" for the desktop that lets you keep an eye on what's going on woth various system resources. Go up to the top taskbar and click on

System - Administration - Synaptic Package Manager

normal user password, not SuperUser/Root one. Use either search tool (i prefer the "Search" button because it looks in package descriptions as well as titles so i can be a lot more vague), find "conky", right-click to install and then click the "Apply" button. The conky configuration file is in your 'username' folder but is a hidden file called "conky.rc" and you can modify this to see all kinds of interesting things about your system. Mostly it's extremely light on system resources but you can add some quite heavy abilities to it, although the comments section in the cofig file warns you about what not to try ;)

I hope something here helps!
Good luck and regards from
Tom :)

From the MS article:

"Significant chunks of address space below 4GB (the highest address accessible via 32-bit) get reserved for use by system hardware:

    • BIOS – including ACPI and legacy video support

    • PCI bus including bridges etc.

    • PCI Express support will reserve at least 256MB, up to 768MB depending on graphics card installed memory

What this means is a typical system may see between ~256MB and 1GB of address space below 4GB reserved for hardware use that the OS cannot access."

Note that this information is operating system independent.

It's still not clear where the fourth Gbyte on my new laptop goes.

On my old 1 Gbyte laptop the system monitor shows 938 Mbyte available, so less than 100 Mbyte disappears.

I would like to believe that the fourth gigabyte is not wasted, but gets used by the graphics card. Am I deceiving myself?

More than 4gigabytes of ram and 32 bits Ubuntu release please read: http://ubuntuforums.org/showthread.php?t=853678

Hope this helps

Fabián Rodríguez (magicfab) said : #9

Fabián Rodríguez suggests this article as an answer to your question:
FAQ #669: “I have 4GB or more of RAM but can't see it in Ubuntu. How can I enable support for all my RAM ?”.

Can you help with this problem?

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