I'm running my new computer which has 8GB of RAM installed, the memory modules show in the BIOS screen and dmidecode, but the total is only 4GB
Only 4GB is visible in /proc/meminfo
uname -a
Linux localhost 3.0.6-gentoo #2 SMP PREEMPT Sat Nov 19 10:45:22 GMT-- x86_64 AMD
Phenom(tm) II X4 955 Processor AuthenticAMD GNU/Linux
The result of /proc/meminfo is as follows: (thanks Andrey)
MemTotal: 4021348 kB
MemFree: 1440280 kB
Buffers: 23696 kB
Cached: 1710828 kB
SwapCached: 4956 kB
Active: 1389904 kB
Inactive: 841364 kB
Active(anon): 1337812 kB
Inactive(anon): 714060 kB
Active(file): 52092 kB
Inactive(file): 127304 kB
Unevictable: 32 kB
Mlocked: 32 kB
SwapTotal: 8388604 kB
SwapFree: 8047900 kB
Dirty: 0 kB
Writeback: 0 kB
AnonPages: 492732 kB
Mapped: 47528 kB
Shmem: 1555120 kB
Slab: 267724 kB
SReclaimable: 177464 kB
SUnreclaim: 90260 kB
KernelStack: 1176 kB
PageTables: 12148 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
WritebackTmp: 0 kB
CommitLimit: 10399276 kB
Committed_AS: 3293896 kB
VmallocTotal: 34359738367 kB
VmallocUsed: 317008 kB
VmallocChunk: 34359398908 kB
AnonHugePages: 120832 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 2048 kB
DirectMap4k: 23552 kB
DirectMap2M: 3088384 kB
DirectMap1G: 1048576 kB
I have tried using mem=8G as a kernel boot parameter, I read a post about setting HIGHMEM64G to yes, before realising that only applies to 32bit kernels.
Trying dmidecode -t memory
SMBIOS 2.7 present.
Handle 0x0026, DMI type 16, 23 bytes
Physical Memory Array
Location: System Board Or Motherboard
Use: System Memory
Error Correction Type: Multi-bit ECC
Maximum Capacity: 32 GB
Error Information Handle: Not Provided
Number Of Devices: 4
Handle 0x0028, DMI type 17, 34 bytes
Memory Device
Array Handle: 0x0026
Error Information Handle: Not Provided
Total Width: 64 bits
Data Width: 64 bits
Size: 4096 MB
Form Factor: DIMM
Set: None
Locator: DIMM0
Bank Locator: BANK0
Type: <OUT OF SPEC>
Type Detail: Synchronous
Speed: 1333 MHz
Manufacturer: Manufacturer0
Serial Number: SerNum0
Asset Tag: AssetTagNum0
Part Number: Array1_PartNumber0
Rank: Unknown
Handle 0x002A, DMI type 17, 34 bytes
Memory Device
Array Handle: 0x0026
Error Information Handle: Not Provided
Total Width: Unknown
Data Width: 64 bits
Size: No Module Installed
Form Factor: DIMM
Set: None
Locator: DIMM1
Bank Locator: BANK1
Type: Unknown
Type Detail: Synchronous
Speed: Unknown
Manufacturer: Manufacturer1
Serial Number: SerNum1
Asset Tag: AssetTagNum1
Part Number: Array1_PartNumber1
Rank: Unknown
Handle 0x002C, DMI type 17, 34 bytes
Memory Device
Array Handle: 0x0026
Error Information Handle: Not Provided
Total Width: 64 bits
Data Width: 64 bits
Size: 4096 MB
Form Factor: DIMM
Set: None
Locator: DIMM2
Bank Locator: BANK2
Type: <OUT OF SPEC>
Type Detail: Synchronous
Speed: 1333 MHz
Manufacturer: Manufacturer2
Serial Number: SerNum2
Asset Tag: AssetTagNum2
Part Number: Array1_PartNumber2
Rank: Unknown
Handle 0x002E, DMI type 17, 34 bytes
Memory Device
Array Handle: 0x0026
Error Information Handle: Not Provided
Total Width: Unknown
Data Width: 64 bits
Size: No Module Installed
Form Factor: DIMM
Set: None
Locator: DIMM3
Bank Locator: BANK3
Type: Unknown
Type Detail: Synchronous
Speed: Unknown
Manufacturer: Manufacturer3
Serial Number: SerNum3
Asset Tag: AssetTagNum3
Part Number: Array1_PartNumber3
Rank: Unknown
My motherboard is a ASUS M5 A99X EVO there are mentions of similar issues on other boards solved by fireware upgrades. I am on the latest firmware, it seems to have made the issue worse.