[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)
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我的计算机用的是intel的ICH7南桥。
* r5 M; m- a' Q* z8 D, Z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:
2 Z7 n; [- z. V+ K( j$ AFF70 0000h – FF7F FFFFh
7 Y8 I2 {* b, U/ E, A9 ^, qFF30 0000h – FF3F FFFFh
在这里 IDSEL 如何理解。
8 r# g9 b* z9 N8 X! C' rFWH_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.
8 R) _' r+ o0 \$ R; O  `3 e0 = Disable.
1 = Enable the following ranges for the Firmware Hub
FF70 0000h – FF7F FFFFh
* k7 X, l" }- y7 y' [( xFF30 0000h – FF3F FFFFh
0 W: o& f  V1 O. f# C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？
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7 O- i: Q: _+ h4 {7 W/ U; s/ U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.
! q5 o3 P4 k7 u0 f% M' ~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
4 V% e! n. M9 H+ U( e% Udecode 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
2 Y7 i# p- p2 J& k( r7 va standby power state.

( \0 _6 m' V' Q# n' j详见LPC spec:
http://www.intel.com/design/chipsets/industry/25128901.pdf
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  w2 y- _& J- P5 _9 f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.