我在有 8GB RAM 的新笔记本电脑 (Asus X550ZA) 上运行 Linux (Mint 17)。bios 显示 8GB，但当我显示 /proc/meminfo 时，它只显示 3.4GB：
$ sudo cat /proc/meminfo
MemTotal: 3411176 kB
MemFree: 122224 kB
MemAvailable: 1924580 kB
当我显示已安装的物理内存时，它显示 8GB。那么我的其他 4.5 GB 内存发生了什么？是什么分配了这些内存？哦，我正在运行 64 位操作系统（Linux gregh-X550ZA 3.19.0-33-generic #38~14.04.1-Ubuntu SMP Fri Nov 6 18:17:28 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux）
$ sudo dmidecode --type memory
Handle 0x0031, DMI type 16, 23 bytes
Physical Memory Array
Location: System Board Or Motherboard
Use: System Memory
Error Correction Type: None
Maximum Capacity: 8 GB
Error Information Handle: Not Provided
Number Of Devices: 2
Handle 0x0033, DMI type 17, 40 bytes
Memory Device
Array Handle: 0x0031
Error Information Handle: Not Provided
Total Width: 64 bits
Data Width: 64 bits
Size: 4096 MB
Form Factor: SODIMM
Set: None
Locator: DIMM 0
Bank Locator: CHANNEL A
Type: DDR3
Type Detail: Synchronous Unbuffered (Unregistered)
Speed: 1600 MHz
Manufacturer: Hynix/Hyundai
Serial Number: 1219ADB5
Asset Tag: A1_AssetTagNum0
Part Number: HMT451S6BFR8A-PB
Rank: 1
Configured Clock Speed: 1600 MHz
Minimum voltage: 1.350 V
Maximum voltage: 1.500 V
Configured voltage: 1.500 V
Handle 0x0034, DMI type 17, 40 bytes
Memory Device
Array Handle: 0x0031
Error Information Handle: Not Provided
Total Width: 64 bits
Data Width: 64 bits
Size: 4096 MB
Form Factor: SODIMM
Set: None
Locator: DIMM 0
Bank Locator: CHANNEL B
Type: DDR3
Type Detail: Synchronous Unbuffered (Unregistered)
Speed: 1600 MHz
Manufacturer: Hynix/Hyundai
Serial Number: 1259ADB8
Asset Tag: A1_AssetTagNum1
Part Number: HMT451S6BFR8A-PB
Rank: 1
Configured Clock Speed: 1600 MHz
Minimum voltage: 1.350 V
Maximum voltage: 1.500 V
Configured voltage: 1.500 V