[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。
4 v# g. r6 F/ {: a. T& Y在手册上
  p3 Q/ o1 r# d9 {9 Q" xFWH_SEL2—Firmware Hub Select 2 Register (LPC I/F—D31:F0)
+ [) d, X% p8 z" X( X: }" G9 o; cFWH_70_IDSEL — R/W. IDSEL for two, 1-M Firmware Hub memory ranges.
2 g2 x8 t! t& {) T, k% z7 {8 wThe IDSEL programmed in this field addresses the following memory ranges:
FF70 0000h – FF7F FFFFh
! c7 Y, C6 W, @# J& V/ bFF30 0000h – FF3F FFFFh
在这里 IDSEL 如何理解。
FWH_DEC_EN1—Firmware Hub Decode Enable Register
(LPC I/F—D31:F0)
  w% X- ^& C$ s. ^+ T4 pFWH_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
/ L- a6 }8 x( @, |/ w3 t; {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？

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
- L) l( J! J+ z8 Sdecode the cycle to determine which bytes are requested on a read or which bytes to update on a
4 Q3 Z7 F7 B2 t6 Q  Z. rwrite. If there isn’t a match, the Firmware component may discard the rest of the cycle and go into
a standby power state.
3 W, p5 h6 X4 F0 z5 q4 ?7 f/ l
详见LPC spec:
& ~8 R" z$ ~3 ~http://www.intel.com/design/chipsets/industry/25128901.pdf
+ |  l( x5 \5 d3 y# [' H; z0 R: ~
. e5 i4 |. y7 ]( z- X) d5 Q% x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.