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PAE还有4GB吗

tag-icon • tag-icon debian kernel pae
PAE还有4GB吗

试图在带有 PAE 的 32 位 CPU 上获得超过 4GB 的 RAM，但不能。

~# grep -o pae /proc/cpuinfo 
pae
pae
pae
pae
~# uname -a
Linux debian 4.9.0-6-686-pae #1 SMP Debian 4.9.82-1+deb9u3 (2018-03-02) i686 GNU/Linux
~# grep HIGHMEM /boot/config-4.9.0-6-686-pae 
# CONFIG_NOHIGHMEM is not set
# CONFIG_HIGHMEM4G is not set
CONFIG_HIGHMEM64G=y
CONFIG_HIGHMEM=y
# CONFIG_DEBUG_HIGHMEM is not set
~# dmidecode -t memory | grep Enabled
    Enabled Error Correcting Capabilities:
    Enabled Size: 1024 MB (Single-bank Connection)
    Enabled Size: 1024 MB (Single-bank Connection)
    Enabled Size: 1024 MB (Single-bank Connection)
    Enabled Size: 1024 MB (Single-bank Connection)
    Enabled Size: 1024 MB (Single-bank Connection)
    Enabled Size: 1024 MB (Single-bank Connection)

还有

~# free -h
              total        used        free      shared  buff/cache   available
Mem:           3.8G         29M        3.6G         10M        244M        3.5G
Swap:            9G          0B          9G

也许有人可以帮忙，我该看哪里？

答案1

要诊断内存问题，最好从内核启动消息开始；内核打印出它发现的有关系统内存的所有内容。从 的输出开始dmesg，寻找“内存”。

正如您发现的那样，在您的情况下这表明

[ 0.000000] WARNING: BIOS bug: CPU MTRRs don't cover all of memory, losing 2176MB of RAM.
[ 0.000000] WARNING: CPU: 0 PID: 0 at /build/linux-rtbsTs/linux-4.9.82/arch/x86/kernel/cpu/mtrr/cleanup.c:978 mtrr_trim_uncached_memory+0x2f5/0x326

这表明 BIOS 没有为 6GiB 系统正确设置。

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