Re: 4gb ram shows as 3.3gb

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John R Pierce wrote:

but thats neither here nor there, PAE is a universal issue for any x86 32bit system with 4GB+ ram, with PAE disabled, the BIOS, PCI, AGP or PCI-express, etc IO spaces consume anywheres from .5 to 1GB of the 32bit address space. PAE is a hardware workaround implemented in pretty much all Intel and AMD CPUs made in the last 5+ years, and allows the OS to access more than 4GB of physical address space. PAE introduces some hardware overhead because it involves larger page tables and another level of indirection in the TLB lookups.

CentOS 5 installs defaults to PAE off because there are some systems where PAE is crash-happy. Someone here has already explained how to enable PAE and in fact the original poster tried it and is happy with his full 4GB now.

Well, looks like I'm having quite a bit of a problem then. :-(

I have PAE kernel running, and all I see is 3.2Gb of the 4Gb.

dmidecode gives me this (intel chip):

Handle 0x0000, DMI type 0, 20 bytes.
BIOS Information
        Vendor: Intel Corp.
        Version: EV91510A.86A.0482.2006.0222.2350

And later this:

Handle 0x0041, DMI type 19, 15 bytes.
Memory Array Mapped Address
        Starting Address: 0x00000000000
        Ending Address: 0x000C77FFFFF
        Range Size: 3192 MB
        Physical Array Handle: 0x0040
        Partition Width: 0

[snip]

Handle 0x0048, DMI type 17, 27 bytes.
Memory Device
        Array Handle: 0x0040
        Error Information Handle: 0x003F
        Total Width: 64 bits
        Data Width: 64 bits
        Size: 1024 MB
        Form Factor: DIMM
        Set: 2
        Locator: J6H2
        Bank Locator: CHANNEL B DIMM1
        Type: DDR
        Type Detail: Synchronous
        Speed: 400 MHz (2.5 ns)
        Manufacturer: Manufacturer4
        Serial Number: SerNum4
        Asset Tag: AssetTagNum4
        Part Number: PartNum4

Handle 0x0049, DMI type 20, 19 bytes.
Memory Device Mapped Address
        Starting Address: 0x000C0000000
        Ending Address: 0x000C6FFFFFF
        Range Size: 112 MB
        Physical Device Handle: 0x0048
        Memory Array Mapped Address Handle: 0x0041
        Partition Row Position: 2
        Interleave Position: 2
        Interleaved Data Depth: 2


As you can see, the last 1Gb bank is only used at 11%.

Any ideas on why I can't see all 4Gb?

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