[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。
# ^& d* @: Y6 `& g) ]6 i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)
+ U# b3 w8 I  i* I
我的计算机用的是intel的ICH7南桥。
& e( H; Q8 ]  g0 O) c2 C在手册上
" z( q: X* [* u9 j, ~; k7 ]: l+ OFWH_SEL2—Firmware Hub Select 2 Register (LPC I/F—D31:F0)
. q: O8 X( K( i2 j+ Z0 n1 O5 i& KFWH_70_IDSEL — R/W. IDSEL for two, 1-M Firmware Hub memory ranges.
' H7 C( s. T# s7 j$ ~& W6 w5 SThe IDSEL programmed in this field addresses the following memory ranges:
! b& X% _4 k% B+ ~, o5 JFF70 0000h – FF7F FFFFh
FF30 0000h – FF3F FFFFh
( o; i9 K/ R7 Z3 q在这里 IDSEL 如何理解。
FWH_DEC_EN1—Firmware Hub Decode Enable Register
& e" q1 b6 n' L. V5 S1 X(LPC I/F—D31:F0)
FWH_70_EN — R/W. Enables decoding two 1-M Firmware Hub memory ranges.
+ k6 B  p, R) d- \6 W. n$ a- K. ]$ U0 = Disable.
1 = Enable the following ranges for the Firmware Hub
FF70 0000h – FF7F FFFFh
& \9 k6 l0 i0 C3 P: s6 y$ p% ?FF30 0000h – FF3F FFFFh
) ^/ D# H: l+ q9 T! @$ h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),
$ s& M& w% `) P1 l/ @: J% s3 ]- MThis 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
2 F+ Q; L6 J7 adecode 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
a standby power state.
# r  n6 B7 {6 F: X2 G, r! V
8 U$ H1 S; y0 J详见LPC spec:
" c2 @. T0 @6 X1 @http://www.intel.com/design/chipsets/industry/25128901.pdf

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.