TheeCSDump: PSD_PORT

PSD_PORT_IO

PSD_PORT_IO keywords Optional, Default, Can't Block

Description Perform local port I/O.

Some platforms have some non MP specific system ports localized on a per- processor basis. If a local I/O operation may block before completion, I/O can be routed to a specific CPU for processing. This should be done, because an operation which started on one processor is not guaranteed to complete on that processor if execution is blocked. This function gets invoked as the result of a device driver calling DevHelp_Port_IO.

Mode Called in Kernel, and Interrupt Mode.

Entry Pointer to a PORT_IO structure.

Exit
NO_ERROR if the I/O was successful.
-1 if the I/O wasn't successful.

Structures

typedef struct port_io_s {
   ulong_t port;   (Input)
   ulong_t data;   (Input/Output)
   ulong_t flags;  (Input)
} PORT_IO;

port indicates which port to read to, or write from.
data contains the data read from a read request, or the data to write if a write request. If the request uses less the 4 bytes the least significant portion of the data variable is used.
flags indicate what operation to perform.
IO_READ_BYTE Read a byte from the port
IO_READ_WORD Read a word from the port
IO_READ_DWORD Read a dword from the port
IO_WRITE_BYTE Write a byte to the port
IO_WRITE_WORD Write a word to the port
IO_WRITE_DWORD Write a dword to the port

Notes If the I/O performed is to a non-local port, the I/O should be handled as a regular I/O request.

If device drivers or applications access the local ports directly, instead of using the documented interfaces problems may occur.

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PsdPortIo

PSD_PORT_IO