![](http://datasheet.mmic.net.cn/110000/GT-96100A_datasheet_3491740/GT-96100A_70.png)
GT-96100A Advanced Communication Controller
70
Revision 1.0
NOTE: The size register is programmed to 0x03FF.FFFF. This indicates that this BAR requires a hit in the six
MSB (bits 31:26) bits of the PCI address for their to be a hit in the BAR. Therefore, the PCI address
0x1DXX.XXXX is a hit in a BAR programmed to 0x1FXX.XXXX as bits 31-26 of both of these
addresses is 0b0001.11.
Then according to the Remap register, these same bit locations will be remapped to 6b111111. The rest
of the PCI address bits (i.e. [25:0]) remain unchanged. This means that the final PCI slave address will
be 0x3D987654.
3.6.4
Writing to Decode Registers
When a BAR register is written to, the associated remap register is written to, simultaneously. When a remap reg-
ister is written to, only its contents are affected.
Following RESET, the default value of a remap register is equal to its associated BAR decode register.
Unless a specific write operation to a remap register takes place, a 1:1 mapping is maintained. Also, changing a
BAR register’s contents automatically returns its associated space to a 1:1 mapping. This allows for backward
software compatibility with other Galileo Technology devices such as the GT-64010A and the GT-64011 core
logic devices.
3.7
Using the CPU PCI Override
In default, the CPU interface supports 512Mbyte PCI memory address space (256Mbyte on PCI_0 Mem0,
256Mbyte on PCI_0 Mem1). If configured to both PCI_0 and PCI_1, it supports 512Mbyte also on PCI_1. The
CPU PCI override feature enables larger PCI memory address space.
The CPU configuration register includes four PCI override bits - two bits per PCI_0 and two bits per PCI_1. Each
bit pair controls whether the PCI window is 2Gbyte, 1Gbyte, or the default.
Setting the PCI override bits are set to ‘01’, and SysAD bits[31:30] match bits [10:9] of the PCI Mem0 Low
decode address register, the transaction is directed to PCI Mem0. This effectively sets a 1Gbyte window in the
PCI memory address space.
NOTE: If Bits[31:30] do not match bits [10:9] of PCI Mem0 Low decode address register, the address is com-
pared against all other address decode registers.
When PCI override bits are set to ‘10’, and SysAD bit[31] matches bit [10] of the PCI Mem0 Low decode
address register, the transaction is directed to PCI Mem0. This effectively sets a 2Gbyte window to PCI.
NOTE: If bit[31] does not match bit [10] of PCI Mem0 Low decode address register, the address is compared
against all other address decode registers.
If PCI override bits are set to ‘00’ there is no PCI override (default address decoding).