我刚刚将我的电脑升级为 32GB 内存。 BIOS 和lshw都承认所有四个 16GB RAM 模块的存在，但两者都没有free，top并且htop看到实际内存。
$ sudo lshw
adam-potwor
width: 64 bits
capabilities: smbios-3.0 dmi-3.0 smp vsyscall32
configuration: boot=normal chassis=desktop family=To Be Filled By O.E.M. sku=To Be Filled By O.E.M. uuid=00020003-0004-0005-0006-000700080009
*-core
description: Motherboard
product: X399 Taichi
vendor: ASRock
physical id: 0
serial: M80-AA002300154
*-firmware
description: BIOS
vendor: American Megatrends Inc.
physical id: 0
version: P1.50
date: 09/05/2017
size: 64KiB
capacity: 15MiB
capabilities: pci upgrade shadowing cdboot bootselect socketedrom edd int13floppy1200 int13floppy720 int13floppy2880 int5printscreen int9keyboard int14serial int17printer acpi usb biosbootspecification uefi
*-memory
description: System Memory
physical id: 10
slot: System board or motherboard
size: 64GiB
*-bank:0
description: DIMM DDR4 Synchronous Unbuffered (Unregistered) 2134 MHz (0.5 ns)
product: F4-3000C16-16GISB
vendor: Unknown
physical id: 0
serial: 00000000
slot: DIMM 0
size: 16GiB
width: 64 bits
clock: 2134MHz (0.5ns)
*-bank:1
description: DIMM DDR4 Synchronous Unbuffered (Unregistered) 2134 MHz (0.5 ns)
product: F4-3000C16-16GISB
vendor: Unknown
physical id: 1
serial: 00000000
slot: DIMM 1
size: 16GiB
width: 64 bits
clock: 2134MHz (0.5ns)
*-bank:2
description: DIMM DDR4 Synchronous Unbuffered (Unregistered) 2134 MHz (0.5 ns)
product: F4-3000C16-16GISB
vendor: Unknown
physical id: 2
serial: 00000000
slot: DIMM 0
size: 16GiB
width: 64 bits
clock: 2134MHz (0.5ns)
*-bank:3
description: DIMM DDR4 Synchronous Unbuffered (Unregistered) 2134 MHz (0.5 ns)
product: F4-3000C16-16GISB
vendor: Unknown
physical id: 3
serial: 00000000
slot: DIMM 1
size: 16GiB
width: 64 bits
clock: 2134MHz (0.5ns)
*-bank:4
description: [empty]
product: Unknown
vendor: Unknown
physical id: 4
serial: Unknown
slot: DIMM 0
*-bank:5
description: [empty]
product: Unknown
vendor: Unknown
physical id: 5
serial: Unknown
slot: DIMM 1
*-bank:6
description: [empty]
product: Unknown
vendor: Unknown
physical id: 6
serial: Unknown
slot: DIMM 0
*-bank:7
description: [empty]
product: Unknown
vendor: Unknown
physical id: 7
serial: Unknown
slot: DIMM 1
*-cache:0
description: L1 cache
physical id: 12
slot: L1 - Cache
size: 1536KiB
capacity: 1536KiB
clock: 1GHz (1.0ns)
capabilities: pipeline-burst internal write-back unified
configuration: level=1
*-cache:1
description: L2 cache
physical id: 13
slot: L2 - Cache
size: 8MiB
capacity: 8MiB
clock: 1GHz (1.0ns)
capabilities: pipeline-burst internal write-back unified
configuration: level=2
*-cache:2
description: L3 cache
physical id: 14
slot: L3 - Cache
size: 32MiB
capacity: 32MiB
clock: 1GHz (1.0ns)
capabilities: pipeline-burst internal write-back unified
configuration: level=3
*-cpu
description: CPU
product: AMD Ryzen Threadripper 1950X 16-Core Processor
vendor: Advanced Micro Devices [AMD]
physical id: 15
bus info: cpu@0
version: AMD Ryzen Threadripper 1950X 16-Core Processor
serial: Unknown
slot: SP3r2
size: 1888MHz
capacity: 4200MHz
width: 64 bits
clock: 100MHz
capabilities: x86-64 fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp constant_tsc rep_good nopl nonstop_tsc cpuid extd_apicid amd_dcm aperfmperf pni pclmulqdq monitor ssse3 fma cx16 sse4_1 sse4_2 movbe popcnt aes xsave avx f16c rdrand lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw skinit wdt tce topoext perfctr_core perfctr_nb bpext perfctr_llc mwaitx cpb hw_pstate sme ssbd vmmcall fsgsbase bmi1 avx2 smep bmi2 rdseed adx smap clflushopt sha_ni xsaveopt xsavec xgetbv1 xsaves clzero irperf xsaveerptr arat npt lbrv svm_lock nrip_save tsc_scale vmcb_clean flushbyasid decodeassists pausefilter pfthreshold avic v_vmsave_vmload vgif overflow_recov succor smca cpufreq
configuration: cores=16 enabledcores=16 threads=32
$ free -h
total used free shared buff/cache available
Mem: 31G 1.8G 27G 18M 1.8G 29G
Swap: 14G 0B 14G
我使用的是 Ubuntu 18.04
$ uname -r
4.15.0-33-generic
核心。我可以在 AskUbuntu 上发布这个问题，但我有一种感觉，这个问题与内核相关，而不是 Ubuntu 特定的。我当前的 grub 引导条目为
menuentry 'Ubuntu' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-9c791297-4f61-471a-ac23-6228987c316e' {
recordfail
load_video
gfxmode $linux_gfx_mode
insmod gzio
if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
insmod part_gpt
insmod ext2
set root='hd0,gpt1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt1 --hint-efi=hd0,gpt1 --hint-baremetal=ahci0,gpt1 b0fddb5e-191e-4de0-b8bd-543c3e22a22a
else
search --no-floppy --fs-uuid --set=root b0fddb5e-191e-4de0-b8bd-543c3e22a22a
fi
linux /vmlinuz-4.15.0-33-generic root=UUID=9c791297-4f61-471a-ac23-6228987c316e ro rootflags=subvol=@ quiet splash $vt_handoff
initrd /initrd.img-4.15.0-33-generic
}
我还安装了 Windows (tm) 来诊断问题。 Windows 10 64位也只有32GB RAM。它将其他 32GB 诊断为“硬件保留”，这强烈表明主板固件中存在错误。
我还确认我的主板具有最新的 BIOS 版本（截至 2018 年 9 月 7 日）
$ dmesg |grep Memory
[ 0.000000] Memory: 32676352K/33432868K available (12300K kernel code, 2470K rwdata, 4244K rodata, 2408K init, 2416K bss, 756516K reserved, 0K cma-reserved)
[ 0.132315] x86/mm: Memory block size: 128MB
答案1
该问题是由于内存插槽配置不当引起的。将内存更换为A2、B2、C2和D2插槽后，正如Mark Patrick所描述的，解决了所有问题。
所以这个故事的主旨是：当Linux（或Windows）没有使用所有已安装的内存时（即使它看到插槽中的芯片），请检查内存模块是否插入到正确的插槽中。