[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。
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)

我的计算机用的是intel的ICH7南桥。
6 G5 {0 C3 G3 ~" m1 r' k在手册上
- x" {# L. [, \& H( `, g& DFWH_SEL2—Firmware Hub Select 2 Register (LPC I/F—D31:F0)
; W% ]! A: p. T3 n* w$ {) N8 NFWH_70_IDSEL — R/W. IDSEL for two, 1-M Firmware Hub memory ranges.
$ P& J; M& A+ s" {# V/ uThe IDSEL programmed in this field addresses the following memory ranges:
  J( x0 U" `0 A/ s. PFF70 0000h – FF7F FFFFh
FF30 0000h – FF3F FFFFh
在这里 IDSEL 如何理解。
0 J* [% z" R) W7 t0 x! Y% lFWH_DEC_EN1—Firmware Hub Decode Enable Register
: L. E  K  L- x5 n8 g9 Y* n(LPC I/F—D31:F0)
# x" ^' C, W4 J! z8 y$ O* J$ JFWH_70_EN — R/W. Enables decoding two 1-M Firmware Hub memory ranges.
0 = Disable.
1 = Enable the following ranges for the Firmware Hub
FF70 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？
: T: n3 \; i$ V; l7 e9 n
* N$ H! \5 t' O4 _4 ]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.
# h: T" X) A' E6 t/ o9 YThe four bits transmitted over AD[3:0] during this clock are compared with values strapped onto
6 B7 D+ E& S5 W7 M( n5 M# {; Epins on the Firmware component. If there is a match, the Firmware component will continue to
. D2 I% \* r9 U; ^decode the cycle to determine which bytes are requested on a read or which bytes to update on a
write. If there isn’t a match, the Firmware component may discard the rest of the cycle and go into
! f. T' n- C, m+ P2 ^5 }a standby power state.
$ s, f4 D# e% _/ C. s. @
详见LPC spec:
http://www.intel.com/design/chipsets/industry/25128901.pdf

" K% C; q' [& L! ]0 c! L. c8 w( e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.