SetupDesignGuide.pdf - Firmware Encoding Index

Setup Design Guide
DRAFT
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Setup Build Infrastructure
3.1 Setup Build Infrastructure Elements
Many elements are involved in the building of a driver that uses the EFI Setup Infrastructure. No
matter if the driver that is using EFI for configuration of a system board, a network device, or an
embedded controller, they all will follow the same basic steps when assembling the components to
leverage the EFI Setup Infrastructure.
3.1.1 VFR Compiler
Some of the things that the compiler is responsible for are the interpreting of the VFR keywords and
converting them to IFR. The compiler is responsible for detecting situations in the VFR files that
would otherwise cause an invalid binary format output.
The command-line interface for the VFR compiler is:
VFRCOMPILE [drive:][path]VfrSourceFile [drive:][path]StringFile
The input to the compiler is the VFR source file and a Unicode string file. The VFR source file will
contain VFR and likely make #include references to a separate global NVRAM mapping file. All of
these are compiled into an output header file.
The outputs of the compiler are header files that will be used by the driver which will export the data.
3.1.2 NVRAM Mapping File
Many of the op-codes associated with IFR are intended to save the user’s choice to some NV data
location. To enable this feature, a map file must be created so that the EFI setup infrastructure knows
where in an NVRAM variable the data must be stored. This map is also used by hardware specific
drivers that might have configuration data stored in the NVRAM variable. For instance, when a driver
has interest in the state of the SerialPortEnable setting, it will need to include this NVRAM
mapping file to know at what offset this data is located.
struct {
UINT16
SystemPassword[20];
UINT16
ModemInitializationString[60];
UINT8
SerialPortEnable;
UINT16
SamplePieceOfData;
UINT32
MyFavoriteNumber;
} SystemNvRamMap;
Note that the SystemNvRamMap is the name of the structure name that is used to reference data both
for the drivers that are interested in their content and the VFR language itself. For instance, if a
command to display the ModemInitializationString setting was to be written in VFR it might
be done as follows:
text
text = SystemNvRamMap.ModemInitializationString;
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