8.5. Multi-Function Support
Because the Configuration Space is replicated for each function, some Configuration Space Register settings may conflict. Arbitration logic resolves differences when settings contain different values across multiple functions. The arbitration logic implements the rules for resolving conflicts as specified in the PCI Express Base Specification 2.1. Examples of settings that require arbitration include the following features:
- Link Control settings
- Error detection and logging for non-function-specific errors
- Error message collapsing
- Maximum payload size (All functions use the largest specified maximum payload setting.)
Altera strongly recommends that your software configure the Maximum payload size (in the Device Control register) with the same value across all functions.
- Interrupt message collapsing
You can access the Configuration Space Registers for the active function using the LMI interface. In Root Port mode, you can also access the Configuration Space Registers using a Configuration Type TLP. Refer to Type 0 Configuration Space Registers for more information about the Configuration Space Registers.
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