我尝试在新笔记本电脑上安装不同的 Linux 发行版（Ubuntu 12.10 Gnome Remix、Fedora 18、Bridge Linux），但它们都存在内存问题。我的笔记本电脑有 4 GB 内存，但 Ubuntu 只能识别 2.4 GB。显然 BIOS 和 Windows 8 都可以识别所有 4GB。
我的笔记本电脑配置：联想 B590 CPU：英特尔酷睿 i5-3210M 内存：4 GB DDR3-SDRAM 芯片组主板：英特尔 HM77 Express 集成显卡：高清显卡 4000。
丢失的内存可能是从 Intel HD Graphics 借来的？如果是真的，它总是借用固定的最大内存？！
一些有用的命令输出：
midecode --type memory
Array Handle: 0x000B
Error Information Handle: Not Provided
Total Width: 64 bits
Data Width: 64 bits
Size: 4096 MB
Form Factor: SODIMM
Set: None
Locator: ChannelB-DIMM0
Bank Locator: BANK 2
Type: DDR3
Type Detail: Synchronous
Speed: 1600 MHz
Manufacturer: Hynix/Hyundai
Serial Number: 1A21B5B9
Asset Tag: 9876543210
Part Number: HMT351S6EFR8C-PB
Rank: Unknown
Configured Clock Speed: 1600 MHz
输出自free -m：
total used free shared buffers cached
Mem: 2483 1136 1346 0 56 515
-/+ buffers/cache: 563 1919
Swap: 4884 0 4884
输出自cat /proc/meminfo | grep "Mem*"
MemTotal: 2542664 kB
MemFree: 1373552 kB
输出自dmesg | grep -i memory
[ 0.000000] initial memory mapped: [mem 0x00000000-0x1fffffff]
[ 0.000000] Base memory trampoline at [ffff880000097000] 97000 size 24576
[ 0.000000] init_memory_mapping: [mem 0x00000000-0x846f1fff]
[ 0.000000] init_memory_mapping: [mem 0x100000000-0x11e5fffff]
[ 0.000000] Early memory node ranges
[ 0.000000] PM: Registered nosave memory: 000000000009d000 - 00000000000a0000
[ 0.000000] PM: Registered nosave memory: 00000000000a0000 - 00000000000e0000
[ 0.000000] PM: Registered nosave memory: 00000000000e0000 - 0000000000100000
[ 0.000000] PM: Registered nosave memory: 0000000020000000 - 0000000020200000
[ 0.000000] PM: Registered nosave memory: 0000000040004000 - 0000000040005000
[ 0.000000] PM: Registered nosave memory: 00000000846f2000 - 00000000dae9f000
[ 0.000000] PM: Registered nosave memory: 00000000dae9f000 - 00000000daf9f000
[ 0.000000] PM: Registered nosave memory: 00000000daf9f000 - 00000000dafff000
[ 0.000000] PM: Registered nosave memory: 00000000dafff000 - 00000000dfa00000
[ 0.000000] PM: Registered nosave memory: 00000000dfa00000 - 00000000f8000000
[ 0.000000] PM: Registered nosave memory: 00000000f8000000 - 00000000fc000000
[ 0.000000] PM: Registered nosave memory: 00000000fc000000 - 00000000fe800000
[ 0.000000] PM: Registered nosave memory: 00000000fe800000 - 00000000fe810000
[ 0.000000] PM: Registered nosave memory: 00000000fe810000 - 00000000fec00000
[ 0.000000] PM: Registered nosave memory: 00000000fec00000 - 00000000fec01000
[ 0.000000] PM: Registered nosave memory: 00000000fec01000 - 00000000fed08000
[ 0.000000] PM: Registered nosave memory: 00000000fed08000 - 00000000fed09000
[ 0.000000] PM: Registered nosave memory: 00000000fed09000 - 00000000fed10000
[ 0.000000] PM: Registered nosave memory: 00000000fed10000 - 00000000fed1a000
[ 0.000000] PM: Registered nosave memory: 00000000fed1a000 - 00000000fed1c000
[ 0.000000] PM: Registered nosave memory: 00000000fed1c000 - 00000000fed20000
[ 0.000000] PM: Registered nosave memory: 00000000fed20000 - 00000000fee00000
[ 0.000000] PM: Registered nosave memory: 00000000fee00000 - 00000000fee01000
[ 0.000000] PM: Registered nosave memory: 00000000fee01000 - 00000000ffc20000
[ 0.000000] PM: Registered nosave memory: 00000000ffc20000 - 0000000100000000
[ 0.000000] Memory: 2515460k/4691968k available (6711k kernel code, 2027016k absent, 149492k reserved, 6459k data, 928k init)
[ 0.000000] please try 'cgroup_disable=memory' option if you don't want memory cgroups
[ 0.001851] Initializing cgroup subsys memory
[ 0.522565] Freeing initrd memory: 23680k freed
[ 1.430344] Freeing unused kernel memory: 928k freed
[ 1.433360] Freeing unused kernel memory: 1472k freed
[ 1.435653] Freeing unused kernel memory: 1124k freed
[ 1.471316] pci 0000:00:00.0: >detected 65536K stolen memory
[ 16.146844] Non-volatile memory driver v1.3
Linux antonio-Notebook 3.5.0-17-generic #28-Ubuntu SMP
Tue Oct 9 19:31:23 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux
dmesg | grep BIOS-e820
[ 0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009cfff] usable
[ 0.000000] BIOS-e820: [mem 0x000000000009d000-0x000000000009ffff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000000e0000-0x00000000000fffff] reserved
[ 0.000000] BIOS-e820: [mem 0x0000000000100000-0x000000001fffffff] usable
[ 0.000000] BIOS-e820: [mem 0x0000000020000000-0x00000000201fffff] reserved
[ 0.000000] BIOS-e820: [mem 0x0000000020200000-0x0000000040003fff] usable
[ 0.000000] BIOS-e820: [mem 0x0000000040004000-0x0000000040004fff] reserved
[ 0.000000] BIOS-e820: [mem 0x0000000040005000-0x00000000846f1fff] usable
[ 0.000000] BIOS-e820: [mem 0x00000000846f2000-0x00000000dae9efff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000dae9f000-0x00000000daf9efff] ACPI NVS
[ 0.000000] BIOS-e820: [mem 0x00000000daf9f000-0x00000000daffefff] ACPI data
[ 0.000000] BIOS-e820: [mem 0x00000000dafff000-0x00000000df9fffff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000f8000000-0x00000000fbffffff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000fe800000-0x00000000fe80ffff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000fec00000-0x00000000fec00fff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000fed08000-0x00000000fed08fff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000fed10000-0x00000000fed19fff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000fed1c000-0x00000000fed1ffff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000fee00000-0x00000000fee00fff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000ffc20000-0x00000000ffffffff] reserved
[ 0.000000] BIOS-e820: [mem 0x0000000100000000-0x000000011e5fffff] usable