如何在Linux中以编程方式获取物理内存地址范围

Question

如何在Linux中以编程方式获取物理内存地址范围

6

我正在尝试在Linux内核模块中获取系统中所有可用RAM的物理地址范围。我查看了cat /proc/iomem并发现物理内存本身并不连续。我知道为了32位系统的兼容性，PCI和其他外围内存需要在4GB地址范围内。还有DOS的640KB初始值。下面的输出来自x86_64系统。

00000000-00000fff : reserved
00001000-0009d7ff : System RAM //640kB here
0009d800-0009ffff : reserved
000a0000-000bffff : PCI Bus 0000:00
000c0000-000cedff : Video ROM
000e0000-000fffff : reserved
  000f0000-000fffff : System ROM
00100000-daa85fff : System RAM  //~3.5 gb here
  01000000-0177acb8 : Kernel code
  0177acb9-01d1b53f : Kernel data
  01e79000-01fbdfff : Kernel bss
daa86000-daa87fff : reserved
daa88000-dad0efff : System RAM  //some RAM here
dad0f000-dae75fff : reserved
dae76000-dae95fff : ACPI Non-volatile Storage
dae96000-daf1efff : reserved
daf1f000-daf9efff : ACPI Non-volatile Storage
daf9f000-daffefff : ACPI Tables
dafff000-daffffff : System RAM //some RAM here
db000000-df9fffff : reserved
  dba00000-df9fffff : Graphics Stolen Memory
dfa00000-feafffff : PCI Bus 0000:00
  e0000000-efffffff : 0000:00:02.0
  f0000000-f03fffff : 0000:00:02.0
  f0400000-f04fffff : PCI Bus 0000:02
    f0400000-f0403fff : 0000:02:00.0
      f0400000-f0403fff : r8169
    f0404000-f0404fff : 0000:02:00.0
      f0404000-f0404fff : r8169
  f0500000-f05fffff : PCI Bus 0000:01
    f0500000-f0503fff : 0000:01:00.0
      f0500000-f0503fff : bcma-pci-bridge
  f0600000-f0603fff : 0000:00:1b.0
    f0600000-f0603fff : ICH HD audio
  f0604000-f06040ff : 0000:00:1f.3
  f0605000-f060500f : 0000:00:16.0
    f0605000-f060500f : mei_me
  f0608000-f06087ff : 0000:00:1f.2
    f0608000-f06087ff : ahci
  f0609000-f06093ff : 0000:00:1d.0
    f0609000-f06093ff : ehci_hcd
  f060a000-f060a3ff : 0000:00:1a.0
    f060a000-f060a3ff : ehci_hcd
  f8000000-fbffffff : PCI MMCONFIG 0000 [bus 00-3f]
    f8000000-fbffffff : reserved
      f8000000-fbffffff : pnp 00:05
fec00000-fec00fff : reserved
  fec00000-fec003ff : IOAPIC 0
fed00000-fed003ff : HPET 0
  fed00000-fed003ff : PNP0103:00
fed08000-fed08fff : reserved
fed10000-fed19fff : reserved
  fed10000-fed17fff : pnp 00:05
  fed18000-fed18fff : pnp 00:05
  fed19000-fed19fff : pnp 00:05
fed1c000-fed1ffff : reserved
  fed1c000-fed1ffff : pnp 00:05
    fed1f410-fed1f414 : iTCO_wdt
fed20000-fed3ffff : pnp 00:05
fed40000-fed44fff : PCI Bus 0000:00
fed45000-fed8ffff : pnp 00:05
fed90000-fed93fff : pnp 00:05
fee00000-fee00fff : Local APIC
  fee00000-fee00fff : reserved
ff000000-ffffffff : INT0800:00
  ffd80000-ffffffff : reserved
100000000-15fdfffff : System RAM //~1.5 gB here
15fe00000-15fffffff : RAM buffer

我的问题是。 1. 如何使用内核代码获得可以用于DMA的全部RAM。 2. 为什么会有额外的RAM区域？而且为什么RAM没有在某个适当的边界处分割，比如2GB+3GB？ 3. 在Linux中，只有3.5GB的区域会被用于DMA，还是高达1.5GB的区域也可以用于DMA。

- hiteshradia

1个回答

网页内容由stack overflow 提供, 点击上面的

可以查看英文原文，
原文链接

- V K Singh · Accepted Answer

有一些命令可以在Linux终端上用于此操作。两个命令都会显示您的Linux系统中的物理内存地址范围。

cat /proc/meminfo：这将在终端打印该值：

MemTotal:        8027952 kB
MemFree:         3893748 kB
Buffers:          132208 kB
Cached:          1666864 kB
SwapCached:       226556 kB
Active:          1979556 kB
Inactive:        1849480 kB
Active(anon):    1592580 kB
Inactive(anon):   886080 kB
Active(file):     386976 kB
Inactive(file):   963400 kB
Unevictable:          68 kB
Mlocked:              68 kB
SwapTotal:      15624188 kB
SwapFree:       15050964 kB
Dirty:               172 kB
Writeback:             0 kB
AnonPages:       1907548 kB
Mapped:           223484 kB
Shmem:            448696 kB
Slab:             140444 kB
SReclaimable:     101456 kB
SUnreclaim:        38988 kB
KernelStack:        4960 kB
PageTables:        53108 kB
NFS_Unstable:          0 kB
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:    19638164 kB
Committed_AS:    7822876 kB
VmallocTotal:   34359738367 kB
VmallocUsed:      567356 kB
VmallocChunk:   34359151824 kB

使用命令vmstat -s，输出结果如下：

  8027952 K total memory
  4114688 K used memory
  1960100 K active memory
  1849792 K inactive memory
  3913264 K free memory
   132240 K buffer memory
  1667108 K swap cache
 15624188 K total swap
   573224 K used swap
 15050964 K free swap
   931285 non-nice user cpu ticks
     6391 nice user cpu ticks
   152567 system cpu ticks
  7019826 idle cpu ticks
   181109 IO-wait cpu ticks
       19 IRQ cpu ticks
     2262 softirq cpu ticks

还有一条使用dmidecode命令的方法：你可以使用sudo dmidecode -t memory来检查Linux系统中RAM的详细信息。