Intel Extensible Firmware Interface - Manual (Page 732)

Extensible Firmware Interface Specification
16-18 12/01/02 Version 1.10
EFI_DEBUGPORT_PROTOCOL.Read()
Summary
Reads data from the debugport.
Prototype
typedef
EFI_STATUS
(EFIAPI *EFI_DEBUGPORT_READ) (
IN EFI_DEBUGPORT_PROTOCOL
*This,
IN UINT32 Timeout,
IN OUT UINTN *BufferSize,
OUT VOID *Buffer
);
Parameters
This A pointer to the EFI_DEBUGPORT_PROTOCOL instance. Type
EFI_DEBUGPORT_PROTOCOL is defined in Section 16.3.
Timeout The number of microseconds to wait before timing out a read
operation.
BufferSize A pointer to an integer which, on input contains the requested number
of bytes of data to read, and on output contains the actual number of
bytes of data read and returned in
Buffer .
Buffer A pointer to a buffer into which the data read will be saved.
Description
The Read() function reads a specified number of bytes from a debugport. If a timeout error or an
overrun error is detected while data is being read from the debugport, then no more characters will
be read, and
EFI_TIMEOUT will be returned. In all cases the number of bytes actually read is
returned in * BufferSize .
It is the responsibility of the caller to insure all parameters are valid. There is no provision for
parameter checking by
Read() . The implementation behavior when an invalid parameter is
passed is not defined by this specification.
Status Codes Returned
EFI_SUCCESS The data was read.
EFI_DEVICE_ERROR The debugport device reported an error.
EFI_TIMEOUT The operation was stopped due to a timeout or overrun.