[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。
% J0 E* V2 |/ B# ]" c(可以访问原512K的ROM 0xFFF8 0000~0xFFFF FFFF)
1 y( ]% h  |: i* I, q! X9 P! ^
我的计算机用的是intel的ICH7南桥。
在手册上
& C" t) U* h  \; Q- ?( h8 LFWH_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.
$ g7 O* }. h, ]  @( v" e1 b( r2 O1 PThe IDSEL programmed in this field addresses the following memory ranges:
0 X, }" [7 D* C* a  w$ X# ]3 a( jFF70 0000h – FF7F FFFFh
FF30 0000h – FF3F FFFFh
* N# {/ m& f( ]7 l- l3 t在这里 IDSEL 如何理解。
FWH_DEC_EN1—Firmware Hub Decode Enable Register
+ P" p; r# t# M3 l7 }7 b(LPC I/F—D31:F0)
FWH_70_EN — R/W. Enables decoding two 1-M Firmware Hub memory ranges.
  S. M. @" D" m, X! F) Z0 = Disable.
1 = Enable the following ranges for the Firmware Hub
FF70 0000h – FF7F FFFFh
FF30 0000h – FF3F FFFFh
& z2 Z) m9 o# J$ g+ e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？
+ r0 f0 R4 p( r9 Z
谢谢大家了！！！

xtdumpling

IDSEL是LPC spec的一个信号(Device Select),
0 Z5 r! p$ g/ T# _& q) d' M% lThis one clock field is used to indicate which of multiple Firmware components is being selected.
! t8 h7 s0 u$ E/ [The four bits transmitted over AD[3:0] during this clock are compared with values strapped onto
$ {" Z& w, s& ]! Zpins 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
write. If there isn’t a match, the Firmware component may discard the rest of the cycle and go into
4 l8 c5 \/ Q( u7 H3 @* V' Na standby power state.

详见LPC spec:
http://www.intel.com/design/chipsets/industry/25128901.pdf

/ i8 g! z7 F- e( v3 y* s6 C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.