Linux基础：如何找出你的系统所支持的最大内存

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  

如果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: Abbreviated   Installable Languages: 1    eng    Currently Installed Language: eng     Handle 0x0030, DMI type 131, 64 bytes  OEM-specific Type   Header and Data:    83 40 30 00 31 00 00 00 00 00 00 00 00 00 00 00    F8 00 4B 1C FF FF FF FF 01 00 00 00 00 00 07 00    AD 04 04 00 00 00 00 00 C8 00 FF FF 00 00 00 00    00 00 00 00 32 00 00 00 76 50 72 6F 00 00 00 00     Handle 0x0029, DMI type 216, 9 bytes  OEM-specific Type   Header and Data:    D8 09 29 00 01 02 01 00 00   Strings:    INTEL    0000     Handle 0x0000, DMI type 0, 24 bytes  BIOS Information   Vendor: Dell Inc.   Version: A05   Release Date: 08/03/2012   Address: 0xF0000   Runtime Size: 64 kB   ROM Size: 2048 kB   Characteristics:    MCA is supported    PCI is supported    BIOS is upgradeable    BIOS shadowing is allowed    ESCD support is available    Boot from CD is supported    Selectable boot is supported    BIOS ROM is socketed    EDD is supported    5.25"/1.2 MB floppy services are supported (int 13h)    3.5"/720 kB floppy services are supported (int 13h)    3.5"/2.88 MB floppy services are supported (int 13h)    Print screen service is supported (int 5h)    8042 keyboard services are supported (int 9h)    Serial services are supported (int 14h)    Printer services are supported (int 17h)    CGA/mono video services are supported (int 10h)    ACPI is supported    USB legacy is supported    ATAPI Zip drive boot is supported    BIOS boot specification is supported    Targeted content distribution is supported   BIOS Revision: 0.5   Firmware Revision: 0.5     Handle 0x0002, DMI type 2, 15 bytes  Base Board Information   Manufacturer: Dell Inc.   Product Name: 01HXXJ   Version: A05   Serial Number: .JSQ7PA1.CN7117623M00J2.   Asset Tag: Not Specified   Features:    Board is a hosting board    Board is replaceable   Location In Chassis: To Be Filled By O.E.M.   Chassis Handle: 0x0003   Type: Motherboard   Contained Object Handles: 0     Handle 0x0003, DMI type 3, 21 bytes  Chassis Information   Manufacturer: Dell Inc.   Type: Portable   Lock: Not Present   Version: Not Specified   Serial Number: JSR1   Asset Tag: Not Specified   Boot-up State: Safe   Power Supply State: Safe   Thermal State: Safe   Security Status: None   OEM Information: 0x00000000   Height: Unspecified   Number Of Power Cords: 1   Contained Elements: 0     Handle 0x0001, DMI type 1, 27 bytes  System Information   Manufacturer: Dell Inc.   Product Name: Inspiron N5050   Version: Not Specified   Serial Number: JSR1   UUID: 4C4C4544-0053-5110-8029-CAC05241   Wake-up Type: Power Switch   SKU Number: To be filled by O.E.M.   Family:           Handle 0x0024, DMI type 208, 12 bytes  OEM-specific Type   Header and Data:    D0 0C 24 00 02 05 FE 00 04 05 01 02   Strings:    20120323    20120323     Handle 0x0011, DMI type 10, 6 bytes  On Board Device Information   Type: Video   Status: Enabled   Description: Mobile Intel SandyBridge HD Graphics     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: 0009F2   Asset Tag: 54114000     Part Number: JM1066-4G     Rank: Unknown     Handle 0x0031, DMI type 127, 4 bytes  End Of Table  

好了，就是这样。

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