大多数情况下你可以从BIOS、产品目录或者干脆手动找出你的系统所持的最大内存。这里，我们介绍一种简单有用的技巧——使用dmidecode来找出系统支持的最大内存，这样你就无需打开机箱或者参照BIOS和产品目录了。
什么是 dmidecode
就像你可能知道的一样， dmidecode是一个将计算机DMI（又名SMBIOS）表的内容转换为可读格式的工具。这个表包含了系统硬件组件的介绍以及其他一些如序列号和IOS版本等有用的信息。使用dmidecode你能够获取此项信息，而无需去探测真实的硬件。
找出你的系统所支持的最大内存
请确定你已经在系统中安装了dmidecode，我觉得你的操作系统应该已经自动安装过了，不过并不非常确定。
在基于Deb的系统中安装
sudo apt-get install dmidecode
在基于RPM的系统中安装
sudo yum install dmidecode
在SUSE/openSUSE中安装
sudo zypper in dmidecode
好了，我们已经安装了dmidecode，接下来让我们找出支持的最大内存。输入以下命令：
sudo dmidecode -t 16
输出样本
# dmidecode 2.12
SMBIOS 2.6 present.
Handle 0x0014, DMI type 16, 15 bytes
Physical Memory Array
Location: System Board Or Motherboard
Use: System Memory
Error Correction Type: None
Maximum Capacity: 16 GB
Error Information Handle: Not Provided
Number Of Devices: 2
就像你看到的，我的系统支持最大内存到16G，并且有两个内存插槽，简单吧？
接下来，让我们找出现在已经安装的内存的详细信息。
sudo dmidecode -t 17
输出样本
# dmidecode 2.12
SMBIOS 2.6 present.
Handle 0x0017, DMI type 17, 28 bytes
Memory Device
Array Handle: 0x0014
Error Information Handle: 0x0000
Total Width: Unknown
Data Width: Unknown
Size: No Module Installed
Form Factor: DIMM
Set: None
Locator: DIMM_B
Bank Locator: BANK 2
Type: Unknown
Type Detail: None
Speed: Unknown
Manufacturer: Not Specified
Serial Number: Not Specified
Asset Tag: Not Specified
Part Number: Not Specified
Rank: Unknown
Handle 0x0015, DMI type 17, 28 bytes
Memory Device
Array Handle: 0x0014
Error Information Handle: 0x0000
Total Width: 64 bits
Data Width: 64 bits
Size: 4096 MB
Form Factor: SODIMM
Set: None
Locator: DIMM_A
Bank Locator: BANK 0
Type: DDR3
Type Detail: Synchronous
Speed: 1067 MHz
Manufacturer: 014F
Serial Number: 00092AF2
Asset Tag: 54114000
Part Number: JM1066KSN-4G
Rank: Unknown
就像上边输出的一样，我在插槽1里边安装了一个内存条。内存大小为4G，类型为DDR3，速度为1067 MHz。
同样的，我们可以通过下边命令得到完整的内存信息。
sudo dmidecode -t memory sudo dmidecode -t memory | less sudo dmidecode -t memory | more
输出样本
# dmidecode 2.12
SMBIOS 2.6 present.
Handle 0x0014, DMI type 16, 15 bytes
Physical Memory Array
Location: System Board Or Motherboard
Use: System Memory
Error Correction Type: None
Maximum Capacity: 16 GB
Error Information Handle: Not Provided
Number Of Devices: 2
Handle 0x0017, DMI type 17, 28 bytes
Memory Device
Array Handle: 0x0014
Error Information Handle: 0x0000
Total Width: Unknown
Data Width: Unknown
Size: No Module Installed
Form Factor: DIMM
Set: None
Locator: DIMM_B
Bank Locator: BANK 2
Type: Unknown
Type Detail: None
Speed: Unknown
Manufacturer: Not Specified
Serial Number: Not Specified
Asset Tag: Not Specified
Part Number: Not Specified
Rank: Unknown
Handle 0x0015, DMI type 17, 28 bytes
Memory Device
Array Handle: 0x0014
Error Information Handle: 0x0000
Total Width: 64 bits
Data Width: 64 bits
Size: 4096 MB
Form Factor: SODIMM
Set: None
Locator: DIMM_A
Bank Locator: BANK 0
Type: DDR3
Type Detail: Synchronous
Speed: 1067 MHz
Manufacturer: 014F
Serial Number: 00092AF2
Asset Tag: 54114000
Part Number: JM1066KSN-4G
Rank: Unknown
假如你好奇想要知道整个系统的详细信息，例如主板、内存、BIOS等，那么可以输入以下命令来获取。
sudo dmidecode
输出样本
# dmidecode 2.12 SMBIOS 2.6 present. 48 structures occupying 2173 bytes. Table at 0x000EB840.
Handle 0xDA00, DMI type 218, 251 bytes OEM-specific Type Header and Data: DA FB 00 DA B2 00 0D 5F 0F 37 40 7D 00 00 00 00 00 7E 00 01 00 00 00 DC 01 00 80 02 00 DD 01 00 80 03 00 75 01 01 80 01 00 76 01 02 80 01 00 2D 01 03 80 01 00 2E 01 03 80 00 00 81 01 07 80 00 00 82 01 07 80 01 00 83 01 08 80 00 00 84 01 08 80 01 00 85 01 06 80 00 00 86 01 06 80 01 00 58 02 05 80 00 00 57 02 05 80 01 00 9C 00 02 00 01 00 9B 00 02 00 00 00 8A 01 03 00 01 00 89 01 03 00 00 00 7F 01 04 00 00 00 80 01 04 00 01 00 53 01 05 00 00 00 52 01 05 00 01 00 7B 01 06 00 00 00 7C 01 06 00 01 00 94 01 07 00 00 00 93 01 07 00 01 00 7D 00 08 00 00 00 2D 00 09 00 01 00 2E 00 09 00 00 00 6E 00 0A 00 00 00 95 00 0B 00 01 00 96 00 0B 00 00 00 2F 02 0C 00 01 00 30 02 0C 00 00 00 50 02 0D 00 00 00 51 02 0D 00 01 00 52 02 0D 00 02 00 FF FF 00 00 00 00 Handle 0xDA01, DMI type 218, 59 bytes OEM-specific Type Header and Data: DA 3B 01 DA B2 00 0D 5F 0F 37 40 53 02 0D 00 03 00 54 02 0D 00 04 00 56 02 0D 00 05 00 4B 01 0E 00 01 00 4A 01 0E 00 00 00 EA 00 0F 00 01 00 EB 00 0F 00 00 00 FF FF 00 00 00 00 Handle 0x0004, DMI type 4, 42 bytes Processor Information Socket Designation: CPU 1 Type: Central Processor Family: Core i3 Manufacturer: Intel ID: A7 06 03 01 FF FB AB BE Signature: Type 0, Family 6, Model 42, Stepping 7 Flags: FPU (Floating-point unit on-chip) VME (Virtual mode extension) DE (Debugging extension) PSE (Page size extension) TSC (Time stamp counter) MSR (Model specific registers) PAE (Physical address extension) MCE (Machine check exception) CX8 (CMPXCHG8 instruction supported) APIC (On-chip APIC hardware supported) SEP (Fast system call) MTRR (Memory type range registers) PGE (Page global enable) MCA (Machine check architecture) CMOV (Conditional move instruction supported) PAT (Page attribute table) PSE-36 (36-bit page size extension) CLFSH (CLFLUSH instruction supported) DS (Debug store) ACPI (ACPI supported) MMX (MMX technology supported) FXSR (FXSAVE and FXSTOR instructions supported) SSE (Streaming SIMD extensions) SSE2 (Streaming SIMD extensions 2) SS (Self-snoop) HTT (Multi-threading) TM (Thermal monitor supported) PBE (Pending break enabled) Version: Intel(R) Core(TM) i3-2350M CPU @ 2.30GHz Voltage: 1.1 V External Clock: 100 MHz Max Speed: 2300 MHz Current Speed: 2300 MHz Status: Populated, Enabled Upgrade: Other L1 Cache Handle: 0x0005 L2 Cache Handle: 0x0006 L3 Cache Handle: 0x0007 Serial Number: To Be Filled By O.E.M. Asset Tag: To Be Filled By O.E.M. Part Number: To Be Filled By O.E.M. Core Count: 2 Core Enabled: 1 Thread Count: 2 Characteristics: 64-bit capable Handle 0x0005, DMI type 7, 19 bytes Cache Information Socket Designation: L1-Cache Configuration: Enabled, Not Socketed, Level 1 Operational Mode: Write Back Location: Internal Installed Size: 64 kB Maximum Size: 64 kB Supported SRAM Types: Other Installed SRAM Type: Other Speed: Unknown Error Correction Type: None System Type: Unified Associativity: 8-way Set-associative Handle 0x0006, DMI type 7, 19 bytes Cache Information Socket Designation: L2-Cache Configuration: Enabled, Not Socketed, Level 2 Operational Mode: Varies With Memory Address Location: Internal Installed Size: 512 kB Maximum Size: 512 kB Supported SRAM Types: Other Installed SRAM Type: Other Speed: Unknown Error Correction Type: None System Type: Unified Associativity: 8-way Set-associative Handle 0x0007, DMI type 7, 19 bytes Cache Information Socket Designation: L3-Cache Configuration: Enabled, Not Socketed, Level 3 Operational Mode: Varies With Memory Address Location: Internal Installed Size: 3072 kB Maximum Size: 3072 kB Supported SRAM Types: Other Installed SRAM Type: Other Speed: Unknown Error Correction Type: None System Type: Unified Associativity: Other Handle 0x0008, DMI type 8, 9 bytes Port Connector Information Internal Reference Designator: J1A1 Internal Connector Type: None External Reference Designator: PS2Mouse External Connector Type: PS/2 Port Type: Mouse Port Handle 0x0009, DMI type 8, 9 bytes Port Connector Information Internal Reference Designator: J1A1 Internal Connector Type: None External Reference Designator: Keyboard External Connector Type: PS/2 Port Type: Keyboard Port Handle 0x000A, DMI type 8, 9 bytes Port Connector Information Internal Reference Designator: J2A2B Internal Connector Type: None External Reference Designator: Video External Connector Type: DB-15 female Port Type: Video Port Handle 0x000B, DMI type 8, 9 bytes Port Connector Information Internal Reference Designator: J3A1 Internal Connector Type: None External Reference Designator: USB1 External Connector Type: Access Bus (USB) Port Type: USB Handle 0x000C, DMI type 8, 9 bytes Port Connector Information Internal Reference Designator: J3A1 Internal Connector Type: None External Reference Designator: USB2 External Connector Type: Access Bus (USB) Port Type: USB Handle 0x000D, DMI type 8, 9 bytes Port Connector Information Internal Reference Designator: J3A1 Internal Connector Type: None External Reference Designator: USB3 External Connector Type: Access Bus (USB) Port Type: USB Handle 0x000E, DMI type 8, 9 bytes Port Connector Information Internal Reference Designator: J5A1 Internal Connector Type: None External Reference Designator: LAN External Connector Type: RJ-45 Port Type: Network Port Handle 0x000F, DMI type 9, 17 bytes System Slot Information Designation: J6B2 Type: x16 PCI Express Current Usage: In Use Length: Long ID: 0 Characteristics: 3.3 V is provided Opening is shared PME signal is supported Bus Address: 0000:00:01.0 Handle 0x0010, DMI type 9, 17 bytes System Slot Information Designation: J6B1 Type: x1 PCI Express Current Usage: In Use Length: Short ID: 1 Characteristics: 3.3 V is provided Opening is shared PME signal is supported Bus Address: 0000:00:1c.3 Handle 0x0012, DMI type 11, 5 bytes OEM Strings String 1: Dell System String 2: 5[0003] String 3: 13[P18F] Handle 0x0013, DMI type 12, 5 bytes System Configuration Options Option 1: To Be Filled By O.E.M. Handle 0x001C, DMI type 21, 7 bytes Built-in Pointing Device Type: Touch Pad Interface: Bus Mouse Buttons: 2 Handle 0x001D, DMI type 22, 26 bytes Portable Battery Location: Sys. Battery Bay Manufacturer: Sanyo Serial Number: 5390 Name: DELL 4YRJH22 Chemistry: Lithium Ion Design Capacity: 45000 mWh Design Voltage: 10800 mV SBDS Version: 1.0 Maximum Error: 2% SBDS Manufacture Date: 2012-02-28 OEM-specific Information: 0x00000001 Handle 0x001E, DMI type 32, 20 bytes System Boot Information Status: No errors detected Handle 0x0020, DMI type 27, 12 bytes Cooling Device Type: Fan Status: OK OEM-specific Information: 0x00000000 Handle 0x0021, DMI type 28, 20 bytes Temperature Probe Description: CPU Internal Temperature Location: Processor Status: OK Maximum Value: 127.0 deg C Minimum Value: 0.0 deg C Resolution: 1.000 deg C Tolerance: 0.5 deg C Accuracy: Unknown OEM-specific Information: 0x00000000 Handle 0xB000, DMI type 176, 5 bytes OEM-specific Type Header and Data: B0 05 00 B0 00 Handle 0xB100, DMI type 177, 12 bytes OEM-specific Type Header and Data: B1 0C 00 B1 1A 0E 00 00 00 00 00 00 Handle 0x0025, DMI type 209, 12 bytes OEM-specific Type Header and Data: D1 0C 25 00 00 00 00 03 05 01 00 03 Handle 0x0026, DMI type 210, 12 bytes OEM-specific Type Header and Data: D2 0C 26 00 00 00 00 03 05 20 01 03 Handle 0x0027, DMI type 211, 13 bytes OEM-specific Type Header and Data: D3 0D 27 00 01 00 00 00 00 02 03 04 04 Strings: Front Handle 0x0028, DMI type 212, 57 bytes OEM-specific Type Header and Data: D4 39 28 00 70 00 71 00 01 49 50 48 9C 00 49 FC 01 9B 00 49 FC 00 7F 01 4A FB 04 80 01 4A FB 00 53 01 4A F7 08 52 01 4A F7 08 7B 01 4A EF 10 7C 01 4A EF 10 FF FF 00 00 00 Handle 0x002A, DMI type 217, 8 bytes OEM-specific Type Header and Data: D9 08 2A 00 01 02 00 00 Strings: Handle 0x002B, DMI type 219, 11 bytes OEM-specific Type Header and Data: DB 0B 2B 00 00 01 02 03 00 04 05 Strings: Handle 0x002C, DMI type 220, 22 bytes OEM-specific Type Header and Data: DC 16 2C 00 01 F0 00 00 02 F0 00 00 00 00 03 F0 04 F0 00 00 00 00 Handle 0x002D, DMI type 221, 19 bytes OEM-specific Type Header and Data: DD 13 2D 00 00 00 00 00 00 03 00 00 00 00 00 00 00 00 00 Handle 0x002E, DMI type 222, 16 bytes OEM-specific Type Header and Data: DE 10 2E 00 01 08 FF FF 00 00 00 00 00 00 00 00 Handle 0x0014, DMI type 16, 15 bytes Physical Memory Array Location: System Board Or Motherboard Use: System Memory Error Correction Type: None Maximum Capacity: 16 GB Error Information Handle: Not Provided Number Of Devices: 2 Handle 0x0016, DMI type 20, 19 bytes Memory Device Mapped Address Starting Address: 0x00000000000 Ending Address: 0x000FFFFFFFF Range Size: 4 GB Physical Device Handle: 0x0015 Memory Array Mapped Address Handle: 0x0018 Partition Row Position: 1 Interleave Position: 1 Interleaved Data Depth: 1 Handle 0x0017, DMI type 17, 28 bytes Memory Device Array Handle: 0x0014 Error Information Handle: 0x0000 Total Width: Unknown Data Width: Unknown Size: No Module Installed Form Factor: DIMM Set: None Locator: DIMM_B Bank Locator: BANK 2 Type: Unknown Type Detail: None Speed: Unknown Manufacturer: Not Specified Serial Number: Not Specified Asset Tag: Not Specified Part Number: Not Specified Rank: Unknown Handle 0x0018, DMI type 19, 15 bytes Memory Array Mapped Address Starting Address: 0x00000000000 Ending Address: 0x000FFFFFFFF Range Size: 4 GB Physical Array Handle: 0x0014 Partition Width: 2 Handle 0x002F, DMI type 13, 22 bytes BIOS Language Information Language Description Format: Abbre