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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