我在运行 Ubuntu 12.04 的 Thinkpad X60 上安装了 4GB RAM。然后我安装了启用 PAE 的内核。现在uname -r输出
3.2.0-50-generic-pae
我的 CPU 支持 PAE：
$ grep pae /proc/cpuinfo
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx constant_tsc arch_perfmon bts aperfmperf pni monitor vmx est tm2 xtpr pdcm dtherm
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx constant_tsc arch_perfmon bts aperfmperf pni monitor vmx est tm2 xtpr pdcm dtherm
BIOS 报告 4096MB RAM。
然而free输出
total used free shared buffers cached
Mem: 3088452 2264192 824260 0 168056 852880
-/+ buffers/cache: 1243256 1845196
Swap: 2085884 0 2085884
怎么了？
编辑：这是 e820 dmesg 部分：
[ 0.000000] BIOS-e820: 0000000000000000 - 000000000009f000 (usable)
[ 0.000000] BIOS-e820: 000000000009f000 - 00000000000a0000 (reserved)
[ 0.000000] BIOS-e820: 00000000000d2000 - 00000000000d4000 (reserved)
[ 0.000000] BIOS-e820: 00000000000dc000 - 0000000000100000 (reserved)
[ 0.000000] BIOS-e820: 0000000000100000 - 00000000bf6d0000 (usable)
[ 0.000000] BIOS-e820: 00000000bf6d0000 - 00000000bf6df000 (ACPI data)
[ 0.000000] BIOS-e820: 00000000bf6df000 - 00000000bf700000 (ACPI NVS)
[ 0.000000] BIOS-e820: 00000000bf700000 - 00000000c0000000 (reserved)
[ 0.000000] BIOS-e820: 00000000f0000000 - 00000000f4000000 (reserved)
[ 0.000000] BIOS-e820: 00000000fec00000 - 00000000fec10000 (reserved)
[ 0.000000] BIOS-e820: 00000000fed00000 - 00000000fed00400 (reserved)
[ 0.000000] BIOS-e820: 00000000fed14000 - 00000000fed1a000 (reserved)
[ 0.000000] BIOS-e820: 00000000fed1c000 - 00000000fed90000 (reserved)
[ 0.000000] BIOS-e820: 00000000fee00000 - 00000000fee01000 (reserved)
[ 0.000000] BIOS-e820: 00000000ff800000 - 0000000100000000 (reserved)
答案1
事实证明这可能是主板/BIOS 问题，并且没有解决方法。类似于64 位和 32 位 12.04 报告内存少 1GB。