Missing RAM on x86_64

["Mike Richards" <mrmikerich@gmail.com>]

Hi, I appear to be missing quite a bit of RAM on an x86_64 system. I
have 1GB installed, but 'free' only shows 878MB:

pokey$ free -m
            total       used       free     shared    buffers     cached
Mem:           878        571        306          0         52        332
-/+ buffers/cache:        186        691
Swap:         1023          0       1023

I'm used to seeing a little bit of RAM missing with 32bit systems, but
146MB seems a bit much. The part of dmesg that concerns the RAM is
shown below. Anyone know what's up here? Is this normal for an x86_64
system?

Linux version 2.6.20.11 (root@pokey) (gcc version 4.1.2) #1 SMP Thu
May 24 18:29:52 GMT 2007
Command line: auto BOOT_IMAGE=2.6.20.11 rw root=801
BIOS-provided physical RAM map:
BIOS-e820: 0000000000000000 - 000000000009fc00 (usable)
BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved)
BIOS-e820: 00000000000e0000 - 0000000000100000 (reserved)
BIOS-e820: 0000000000100000 - 0000000037fd0000 (usable)
BIOS-e820: 0000000037fd0000 - 0000000037fde000 (ACPI data)
BIOS-e820: 0000000037fde000 - 0000000038000000 (ACPI NVS)
BIOS-e820: 00000000fec00000 - 00000000fec01000 (reserved)
BIOS-e820: 00000000fee00000 - 00000000fef00000 (reserved)
BIOS-e820: 00000000ff780000 - 0000000100000000 (reserved)
Entering add_active_range(0, 0, 159) 0 entries of 256 used
Entering add_active_range(0, 256, 229328) 1 entries of 256 used
end_pfn_map = 1048576
DMI 2.3 present.
Entering add_active_range(0, 0, 159) 0 entries of 256 used
Entering add_active_range(0, 256, 229328) 1 entries of 256 used
Zone PFN ranges:
 DMA             0 ->     4096
 DMA32        4096 ->  1048576
 Normal    1048576 ->  1048576
early_node_map[2] active PFN ranges
   0:        0 ->      159
   0:      256 ->   229328
On node 0 totalpages: 229231
 DMA zone: 56 pages used for memmap
 DMA zone: 890 pages reserved
 DMA zone: 3053 pages, LIFO batch:0
 DMA32 zone: 3079 pages used for memmap
 DMA32 zone: 222153 pages, LIFO batch:31
 Normal zone: 0 pages used for memmap
Intel MultiProcessor Specification v1.4
MPTABLE: OEM ID: nVidia   MPTABLE: Product ID: MCP51G/M     MPTABLE:
APIC at: 0xFEE00000
Processor #0 (Bootup-CPU)
I/O APIC #1 at 0xFEC00000.
Setting APIC routing to flat
Processors: 1
Nosave address range: 000000000009f000 - 00000000000a0000
Nosave address range: 00000000000a0000 - 00000000000e0000
Nosave address range: 00000000000e0000 - 0000000000100000
Allocating PCI resources starting at 40000000 (gap: 38000000:c6c00000)
PERCPU: Allocating 25088 bytes of per cpu data
Built 1 zonelists.  Total pages: 225206
Kernel command line: auto BOOT_IMAGE=2.6.20.11 rw root=801
Initializing CPU#0
PID hash table entries: 4096 (order: 12, 32768 bytes)
Console: colour VGA+ 80x25
Dentry cache hash table entries: 131072 (order: 8, 1048576 bytes)
Inode-cache hash table entries: 65536 (order: 7, 524288 bytes)
Checking aperture...
CPU 0: aperture @ 61ba000000 size 32 MB
Aperture too small (32 MB)
No AGP bridge found
Memory: 898964k/917312k available (2235k kernel code, 17744k reserved,
750k data, 200k init)
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