Is System RAM the only section where heap/stack re

问题:

[root@ ~]# cat /proc/iomem 
00000000-0000ffff : reserved
00010000-0009f7ff : System RAM
0009f800-0009ffff : reserved
000ca000-000cbfff : reserved
000dc000-000e3fff : reserved
000e8000-000fffff : reserved
00100000-3fedffff : System RAM
  01000000-013a5eb4 : Kernel code
  013a5eb5-0173e0c7 : Kernel data
  01805000-05d9d4f7 : Kernel bss
3fee0000-3fefefff : ACPI Tables
3feff000-3fefffff : ACPI Non-volatile Storage
3ff00000-3fffffff : System RAM
40000000-40007fff : 0000:00:0f.0
40008000-4000bfff : 0000:00:10.0
d0000000-d7ffffff : 0000:00:0f.0
d8000000-d87fffff : 0000:00:0f.0
d8800000-d881ffff : 0000:00:10.0
  d8800000-d881ffff : mpt
d8820000-d883ffff : 0000:00:10.0
  d8820000-d883ffff : mpt
d8900000-d9cfffff : PCI Bus 0000:02
  d8900000-d890ffff : 0000:02:01.0
    d8900000-d890ffff : e1000
  d8910000-d8910fff : 0000:02:03.0
    d8910000-d8910fff : ehci_hcd
  d8920000-d893ffff : 0000:02:01.0
    d8920000-d893ffff : e1000
d9d00000-d9dfffff : PCI Bus 0000:03
d9e00000-d9efffff : PCI Bus 0000:0b
d9f00000-d9ffffff : PCI Bus 0000:13
da000000-da0fffff : PCI Bus 0000:1b
da100000-da1fffff : PCI Bus 0000:04
da200000-da2fffff : PCI Bus 0000:0c
da300000-da3fffff : PCI Bus 0000:14
da400000-da4fffff : PCI Bus 0000:1c
da500000-da5fffff : PCI Bus 0000:05
da600000-da6fffff : PCI Bus 0000:0d
da700000-da7fffff : PCI Bus 0000:15
da800000-da8fffff : PCI Bus 0000:1d
da900000-da9fffff : PCI Bus 0000:06
daa00000-daafffff : PCI Bus 0000:0e
dab00000-dabfffff : PCI Bus 0000:16
dac00000-dacfffff : PCI Bus 0000:1e
dad00000-dadfffff : PCI Bus 0000:07
dae00000-daefffff : PCI Bus 0000:0f
daf00000-daffffff : PCI Bus 0000:17
db000000-db0fffff : PCI Bus 0000:1f
db100000-db1fffff : PCI Bus 0000:08
db200000-db2fffff : PCI Bus 0000:10
db300000-db3fffff : PCI Bus 0000:18
db400000-db4fffff : PCI Bus 0000:20
db500000-db5fffff : PCI Bus 0000:09
db600000-db6fffff : PCI Bus 0000:11
db700000-db7fffff : PCI Bus 0000:19
db800000-db8fffff : PCI Bus 0000:21
db900000-db9fffff : PCI Bus 0000:0a
dba00000-dbafffff : PCI Bus 0000:12
dbb00000-dbbfffff : PCI Bus 0000:1a
dbc00000-dbcfffff : PCI Bus 0000:22
dbe00000-dbffffff : pnp 00:0c
dc400000-dc9fffff : PCI Bus 0000:02
  dc400000-dc40ffff : 0000:02:01.0
dca00000-dcafffff : PCI Bus 0000:03
dcb00000-dcbfffff : PCI Bus 0000:0b
dcc00000-dccfffff : PCI Bus 0000:13
dcd00000-dcdfffff : PCI Bus 0000:1b
dce00000-dcefffff : PCI Bus 0000:04
dcf00000-dcffffff : PCI Bus 0000:0c
dd000000-dd0fffff : PCI Bus 0000:14
dd100000-dd1fffff : PCI Bus 0000:1c
dd200000-dd2fffff : PCI Bus 0000:05
dd300000-dd3fffff : PCI Bus 0000:0d
dd400000-dd4fffff : PCI Bus 0000:15
dd500000-dd5fffff : PCI Bus 0000:1d
dd600000-dd6fffff : PCI Bus 0000:06
dd700000-dd7fffff : PCI Bus 0000:0e
dd800000-dd8fffff : PCI Bus 0000:16
dd900000-dd9fffff : PCI Bus 0000:1e
dda00000-ddafffff : PCI Bus 0000:07
ddb00000-ddbfffff : PCI Bus 0000:0f
ddc00000-ddcfffff : PCI Bus 0000:17
ddd00000-dddfffff : PCI Bus 0000:1f
dde00000-ddefffff : PCI Bus 0000:08
ddf00000-ddffffff : PCI Bus 0000:10
de000000-de0fffff : PCI Bus 0000:18
de100000-de1fffff : PCI Bus 0000:20
de200000-de2fffff : PCI Bus 0000:09
de300000-de3fffff : PCI Bus 0000:11
de400000-de4fffff : PCI Bus 0000:19
de500000-de5fffff : PCI Bus 0000:21
de600000-de6fffff : PCI Bus 0000:0a
de700000-de7fffff : PCI Bus 0000:12
de800000-de8fffff : PCI Bus 0000:1a
de900000-de9fffff : PCI Bus 0000:22
e0000000-efffffff : PCI MMCONFIG 0 [00-ff]
  e0000000-efffffff : reserved
    e0000000-efffffff : pnp 00:0c
fec00000-fec0ffff : reserved
  fec00000-fec00fff : IOAPIC 0
fee00000-fee00fff : Local APIC
  fee00000-fee00fff : reserved
fffe0000-ffffffff : reserved

Is it true that when we operate on heap/stack,we are actually operating on the System RAM?

回答1:

Well, ultimately you have to be operating on "system RAM" (I assume you mean physical RAM). What else could you be? When the code actually is given cycles by the kernel, the stack and heap data has to be in physical RAM. Along the way it could be swapped out, of course. And its virtual address in the process address space will have no relation to its address in physical RAM when it's swapped in. But it will be living in physical RAM when it's operated on.

回答2:

Well, it's RAM and, when it's assigned to the heap we can refer to it as "system" RAM. To answer your question, though, we can imagine or fantasize a system where the heap resides elsewhere than RAM, but we don't very often see such systems. So, yes, the heap in practical terms lives in RAM. The stack, OTOH, belongs to the running program and it, too, lives in RAM.