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。
via: http://www.unixmen.com/linux-basics-how-to-find-maximum-supported-ram-by-your-system/
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