Networking Silicon — GD82559ER
Note: Bit 3 is set to 1b only if the value 00001000b (8H) is written to this register, and bit 4 is set to 1b only if the value of 00010000b (16H) is written to this register. All other bits are read only and will return a value of 0b on read.
This register is expected to be written by the BIOS and the 82559ER driver should not write to it.
The Latency Timer register is a byte wide register. When the 82559ER is acting as a bus master, this register defines the amount of time, in PCI clock cycles, that it may own the bus.
The Header Type register is a byte read only register. It is
One of the most important functions for enabling superior configurability and ease of use is the ability to relocate PCI devices in address spaces. The 82559ER contains three types of Base Address Registers (BARs). Two are used for memory mapped resources, and one is used for I/O mapping. Each register is 32 bits wide. The least significant bit in the BAR determines whether it represents a memory or I/O space. The figures below show the layout of a BAR for both memory and I/O mapping. After determining this information,
31 | 4 3 2 1 0 | |||
Base Address |
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Prefetchable
Set to 0b in 82559ER
Type
00- locate anywhere in
01- locate below 1 Mbyte
10- locate anywhere in
11- reserved
Memory space indicator
Datasheet | 51 |