[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。
" W  k( w* w$ n- Q$ G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。
2 @& u. m1 K7 Z(可以访问原512K的ROM 0xFFF8 0000~0xFFFF FFFF)

我的计算机用的是intel的ICH7南桥。
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:
FF70 0000h – FF7F FFFFh
FF30 0000h – FF3F FFFFh
0 h/ Y" \  {7 [& m在这里 IDSEL 如何理解。
FWH_DEC_EN1—Firmware Hub Decode Enable Register
(LPC I/F—D31:F0)
FWH_70_EN — R/W. Enables decoding two 1-M Firmware Hub memory ranges.
1 q8 W7 e& L; N, f0 = Disable.
1 = Enable the following ranges for the Firmware Hub
FF70 0000h – FF7F FFFFh
( G# P7 h2 ]8 W; FFF30 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？

! u# S. J" w, O8 Q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
pins on the Firmware component. If there is a match, the Firmware component will continue to
decode the cycle to determine which bytes are requested on a read or which bytes to update on a
" S+ G" Y* K2 f$ V8 |  Fwrite. If there isn’t a match, the Firmware component may discard the rest of the cycle and go into
; M& q$ Z2 j; k1 ^- |3 Xa standby power state.
. J. m, p( y1 V( }/ q7 b7 f
详见LPC spec:
http://www.intel.com/design/chipsets/industry/25128901.pdf
! X8 \% y, T$ K" [6 n0 v
# ^; m* K) P$ E  o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.