以下是在一台有4GB RAM有獨立顯卡(i.e. VGA沒有share到system RAM)的NB上看到的狀況....
1:32bit Linux,開PAE
引用:
00000000-0009fbff : System RAM
0009fc00-0009ffff : reserved
000a0000-000bffff : Video RAM area
000c0000-000cdfff : Video ROM
000ce000-000cefff : Adapter ROM
000f0000-000fffff : System ROM
00100000-bafcffff : System RAM
00200000-003dea29 : Kernel code
003dea2a-004b5e23 : Kernel data
004f6000-0056640f : Kernel bss
bafd0000-bafddfff : ACPI Tables
bafde000-baffffff : ACPI Non-volatile Storage
bbf00000-bdefffff : PCI Bus #02
bdf00000-ddefffff : PCI Bus #04
c0000000-cfffffff : 0000:04:00.0
ddf00000-dfefffff : PCI Bus #05
e0000000-efffffff : pnp 00:0b
f0000000-f3ffffff : PCI CardBus #06
f4000000-f7ffffff : PCI CardBus #06
f8c00000-f8cfffff : PCI Bus #01
f8cc0000-f8cdffff : 0000:01:00.0
f8cff000-f8cfffff : 0000:01:00.0
f8cff000-f8cfffff : r8169
f8d00000-f94fffff : PCI Bus #02
f9500000-fd5fffff : PCI Bus #04
fb000000-fbffffff : 0000:04:00.0
fc000000-fcffffff : 0000:04:00.0
fd5e0000-fd5fffff : 0000:04:00.0
fd600000-fdefffff : PCI Bus #05
fd600000-fd600fff : 0000:05:04.0
fdef0000-fdef7fff : 0000:05:09.0
fdef0000-fdef7fff : 0000:05:09.0
fdefd000-fdefdfff : 0000:05:04.3
fdefe400-fdefe4ff : 0000:05:04.2
fdefe400-fdefe4ff : sdhci:slot0
fdefe800-fdefefff : 0000:05:04.4
fdeff000-fdefffff : 0000:05:04.4
fdeff000-fdeff7ff : ohci1394
fdfb8000-fdfbbfff : 0000:00:10.1
fdfb8000-fdfbbfff : ICH HD audio
fdfbd000-fdfbdfff : 0000:00:0e.0
fdfbd000-fdfbdfff : sata_nv
fdfbe000-fdfbefff : 0000:00:0b.0
fdfbe000-fdfbefff : ohci_hcd
fdfbfc00-fdfbfcff : 0000:00:0b.1
fdfbfc00-fdfbfcff : ehci_hcd
fdfc0000-fdffffff : 0000:00:0a.3
fec00000-fec00fff : reserved
fed00000-fed003ff : HPET 0
fee00000-feefffff : reserved
fefe0000-fefe01ff : pnp 00:07
fff80000-ffffffff : reserved
100000000-144ffffff : System RAM
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我們可以看到系統可以用到的RAM約略被分成兩段,第一段由0x0-0xbafcffff(約3GB-80M),第二段由0x100000000-0x144ffffff(1GB+80M),其中0xc0000000-0xffffffff(共1GB)主要就是被PCI拿去當MMIO的位址用掉了,但要是OS支援PAE/X86-64且H/W支援memory remapping的話其實會被remapping到4GB以後的位址,並不是真的被I/O用掉了,只是如果OS不支援PAE/X86-64或H/W不支援memory remapping的話就只能指望BIOS減少ACPI/PCI MMIO佔用的位址(i.e. ACPI/PCI的MMIO位址其實是由BIOS設定的
),如果能盡量往後挪對這類OS而言能用到的RAM或許可以多榨出個3-500MB吧
....