We have observed that the PC does not boot whenwe have plugged in our PCI card. Our card is processor based architecture with PCI targetinterface on it. To tell the exact thing we can write in to any of the Configuration registers from the processor side except for the Base address registers. In this process we have disabled the ExpansionROM ( 1st bitat offset 30'h of configuration space is set to 0)
When we have looked through the transactions happening on the PCI using a logic Analyzer to find out the problem of PC hang.After the Bios reads the Configuration space and then writes all F's in the Base address registers and reads back to find out theMemory Space required.But in the Expansion Rom base adress it writes FFFFFFFE and when it reads it gets value of 7FFFC000.After thatother cards are configured and the Further transactions cannot be seen.( The bus is idle ). We have also observed that some Master is parking different addresses on the bus and halts at adressFF08062Cand PC fails to boot.
We havefound similar observations with D102GGC2 mother boards too.
Inspite of Disabling the Expansion Rom why is the BIOSnot ignoring the Expansion Rom base address read?.
Is the Bios's corner casethat it simply stucks there.?
A common observation was , these were Dual core PC's
In other Other mother board's we found the that the BIOS ignores the Base adress read andcontinues with other transactions.