About IO Decode (AMD Chipset)

1.Set IO base address in south bridge register
2.Enable Alternative Wide IO Range in south bridge register
3.Enable Wide IO Port in south bridge register
if system still can't open IO decode, we need to check  is occupied by another device using the same IO resource or not. We can check the value in each of PCI bridge offset 0x1C.PCI bridger IO resource is aligned to a 4KB boundary.

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1.設定要做IO decode去設定南橋暫存器的IO Base Adress
2.開啟南橋暫存器的Alternative Wide IO Range
3.開啟南橋暫存器的Wide IO Port
若還是無法開啟IO decode，這時候就要檢查是否有別的device佔用到相同的IO decode的位址，可以先檢查每個PCI bridge的offset 0x1C的值，PCI bridge一次就是佔4K的IO resource。