Hello,

I have a system based on an AMD Athlon(tm) 64 X2 Dual Core Processor 3600+, Gigabyte GA-M61PM-S2 (mother-board) with 8Gb of physical memory. Linux (Debian Etch, kernel 2.6.18 amd64) recognizes only 6.5 Gb.
Does anybody have an idea on how to get 8 Gb memory working in this system?

Thanks.

That almost sounds like you are running a 32bit kernel even though you say amd64. What does uname -a show can you post it, the cat /proc/meminfo, cat /proc/cpuinfo and the lshw output where it shows the memory slots/sticks installed if you would?

Here you go. Thanks.

uname -a
Linux tomjobim 2.6.18-4-amd64 #1 SMP Mon Mar 26 11:36:53 CEST 2007 x86_64 GNU/Linux

-------------------------------
cat /proc/meminfo
MemTotal: 7020332 kB
MemFree: 3103104 kB
Buffers: 125560 kB
Cached: 208132 kB
SwapCached: 0 kB
Active: 3521348 kB
Inactive: 171556 kB
HighTotal: 0 kB
HighFree: 0 kB
LowTotal: 7020332 kB
LowFree: 3103104 kB
SwapTotal: 9767512 kB
SwapFree: 9767512 kB
Dirty: 56 kB
Writeback: 0 kB
AnonPages: 3359344 kB
Mapped: 52328 kB
Slab: 188580 kB
PageTables: 13416 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
CommitLimit: 13277676 kB
Committed_AS: 3563520 kB
VmallocTotal: 34359738367 kB
VmallocUsed: 267528 kB
VmallocChunk: 34359470823 kB

-------------------------------
cat /proc/meminfo
MemTotal: 7020332 kB
MemFree: 3103104 kB
Buffers: 125560 kB
Cached: 208132 kB
SwapCached: 0 kB
Active: 3521348 kB
Inactive: 171556 kB
HighTotal: 0 kB
HighFree: 0 kB
LowTotal: 7020332 kB
LowFree: 3103104 kB
SwapTotal: 9767512 kB
SwapFree: 9767512 kB
Dirty: 56 kB
Writeback: 0 kB
AnonPages: 3359344 kB
Mapped: 52328 kB
Slab: 188580 kB
PageTables: 13416 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
CommitLimit: 13277676 kB
Committed_AS: 3563520 kB
VmallocTotal: 34359738367 kB
VmallocUsed: 267528 kB
VmallocChunk: 34359470823 kB

-------------------------------
cat /proc/cpuinfo
processor : 0
vendor_id : AuthenticAMD
cpu family : 15
model : 75
model name : AMD Athlon(tm) 64 X2 Dual Core Processor 3600+
stepping : 2
cpu MHz : 2009.171
cache size : 256 KB
physical id : 0
siblings : 2
core id : 0
cpu cores : 2
fpu : yes
fpu_exception : yes
cpuid level : 1
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow pni cx16 lahf_lm cmp_legacy svm cr8_legacy
bogomips : 4023.15
TLB size : 1024 4K pages
clflush size : 64
cache_alignment : 64
address sizes : 40 bits physical, 48 bits virtual
power management: ts fid vid ttp tm stc

processor : 1
vendor_id : AuthenticAMD
cpu family : 15
model : 75
model name : AMD Athlon(tm) 64 X2 Dual Core Processor 3600+
stepping : 2
cpu MHz : 2009.171
cache size : 256 KB
physical id : 0
siblings : 2
core id : 1
cpu cores : 2
fpu : yes
fpu_exception : yes
cpuid level : 1
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow pni cx16 lahf_lm cmp_legacy svm cr8_legacy
bogomips : 4018.50
TLB size : 1024 4K pages
clflush size : 64
cache_alignment : 64
address sizes : 40 bits physical, 48 bits virtual
power management: ts fid vid ttp tm stc


-------------------------------
lshw
tomjobim
description: Desktop Computer
width: 32 bits
capabilities: smbios-2.3 dmi-2.3
configuration: boot=normal chassis=desktop
*-core
description: Motherboard
product: M61PM-S2
vendor: Gigabyte Technology Co., Ltd.
physical id: 0
*-firmware
description: BIOS
vendor: Award Software International, Inc.
physical id: 0
version: F3 (09/18/2006)
size: 128KB
capacity: 448KB
capabilities: pci pnp apm upgrade shadowing cdboot bootselect socketedrom edd int13floppy360 int13floppy1200 int13floppy720 int13floppy2880 int5printscreen int9keyboard int14serial int17printer int10video acpi usb ls120boot zipboot biosbootspecification
*-cpu:0
description: CPU
product: AMD Athlon(tm) 64 X2 Dual Core Processor 3600+
vendor: Advanced Micro Devices [AMD]
physical id: 3
bus info: cpu@0
version: AMD Athlon(tm) 64 X2 Dual Core Processor 3600+
slot: Socket M2
size: 2GHz
capacity: 3200MHz
width: 64 bits
clock: 200MHz
capabilities: fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp x86-64 3dnowext 3dnow pni cx16 lahf_lm cmp_legacy svm cr8_legacy
*-cache:0
description: L1 cache
physical id: b
slot: Internal Cache
size: 128KB
capacity: 128KB
capabilities: synchronous internal write-back
*-cache:1
description: L2 cache
physical id: d
slot: External Cache
size: 256KB
capacity: 256KB
capabilities: synchronous internal write-back
*-cpu:1
description: CPU
product: Athlon ( )
vendor: AMD
physical id: 4
bus info: cpu@1
version: AMD Athlon(tm) 64 X2 Dual Core Processor 3600+
slot: Socket M2
size: 2GHz
capacity: 3200MHz
clock: 200MHz
*-cache:0
description: L1 cache
physical id: c
slot: Internal Cache
size: 128KB
capacity: 128KB
capabilities: synchronous internal write-back
*-cache:1 DISABLED
description: L2 cache
physical id: e
slot: External Cache
capacity: 1MB
capabilities: synchronous internal write-through
*-memory:0
description: System Memory
physical id: 1b
slot: System board or motherboard
size: 8GB
*-bank:0
description: DIMM 400 MHz (2.5 ns)
physical id: 0
slot: A0
size: 2GB
width: 64 bits
clock: 400MHz (2.5ns)
*-bank:1
description: DIMM 400 MHz (2.5 ns)
physical id: 1
slot: A1
size: 2GB
width: 64 bits
clock: 400MHz (2.5ns)
*-bank:2
description: DIMM 400 MHz (2.5 ns)
physical id: 2
slot: A2
size: 2GB
width: 64 bits
clock: 400MHz (2.5ns)
*-bank:3
description: DIMM 400 MHz (2.5 ns)
physical id: 3
slot: A3
size: 2GB
width: 64 bits
clock: 400MHz (2.5ns)
*-memory:1 UNCLAIMED
description: RAM memory
product: MCP61 Memory Controller
vendor: nVidia Corporation
physical id: 5
bus info: pci@00:00.0
version: a1
width: 32 bits
clock: 66MHz (15.2ns)
capabilities: bus_master cap_list
configuration: latency=0
...

That says it is running a 64bit kernel so it must be BIOS related somehow I see that your board has a version F7 whereas you have F3 installed you might want to consider upgrading if checking around in there does not yield an option to set it for 64bit mode because what you are seeing here looks like it is using 32bit addressing reserving space for the devices. On my board with 4gb using 64bit I get it all if I boot with 32bit OS then ~3.5gb is available which if you would double it comes to what you are seeing. Another thing the Gigabyte website has a support option where you can submit them a question I have used it a couple of times and they usually only take a couple of days at most to get back to you.

http://www.giga-byte.com.tw/Support/ServiceCenter.aspx

Yes, I updated the BIOS to F7 and it worked!
Thanks for you help!