[请教]BIOS地址映射?

暴雪

原512K的ROM，现换了一个1M的ROM，windows下在 0xFFF0 0000~0xFFF7 FFFF 可以看到追加的512K的内容。
0 b% Z" C5 Z& m但在启动计算机时(BIOS没有初始化计算机），无法访问追加的512K的ROM。
(可以访问原512K的ROM 0xFFF8 0000~0xFFFF FFFF)
; c# V8 {/ f2 b" x
我的计算机用的是intel的ICH7南桥。
' Y' m; n0 C- Z+ x/ P2 ^8 o在手册上
FWH_SEL2—Firmware Hub Select 2 Register (LPC I/F—D31:F0)
FWH_70_IDSEL — R/W. IDSEL for two, 1-M Firmware Hub memory ranges.
The IDSEL programmed in this field addresses the following memory ranges:
- `- Y) A& R* {7 t- b. ]4 {- d2 @FF70 0000h – FF7F FFFFh
1 p: R3 ]. S3 k. O6 qFF30 0000h – FF3F FFFFh
在这里 IDSEL 如何理解。
FWH_DEC_EN1—Firmware Hub Decode Enable Register
( z5 K1 z5 }  \. K" K" C# j4 k(LPC I/F—D31:F0)
FWH_70_EN — R/W. Enables decoding two 1-M Firmware Hub memory ranges.
8 j7 T/ o, \. u7 `0 = Disable.
1 = Enable the following ranges for the Firmware Hub
0 \0 A+ w- p/ M1 D& T; TFF70 0000h – FF7F FFFFh
FF30 0000h – FF3F FFFFh
除了上面的数据区域，还有其它的数据区域控制ROM到内存地址的映射吗？
3 m9 u' _" @  i2 K& T
3 U, A2 {5 B+ S谢谢大家了！！！

xtdumpling

IDSEL是LPC spec的一个信号(Device Select),
This one clock field is used to indicate which of multiple Firmware components is being selected.
The four bits transmitted over AD[3:0] during this clock are compared with values strapped onto
& j) b, [" |$ K2 t. {& gpins on the Firmware component. If there is a match, the Firmware component will continue to
# J: m$ G2 u, e9 idecode the cycle to determine which bytes are requested on a read or which bytes to update on a
% Y3 i# v' e8 w/ k! V/ q6 K" Y0 ?write. If there isn’t a match, the Firmware component may discard the rest of the cycle and go into
# v( n, S  d( f  [* V% Ya standby power state.
6 s3 J" [# r: [3 ?9 i  @/ G
2 k0 f- S2 E% _7 |详见LPC spec:
( c3 T4 ~( ]% A) h0 Y* xhttp://www.intel.com/design/chipsets/industry/25128901.pdf

在ICH 7 中似乎就这几个吧(FWH_SEL1,FWH_SEL2,FWH_DEC_EN1,BIOS_CNTL),据我现在知道的.