_CA_PCI_Read_Config_Byte()

read a byte from the configuration space of a device

Synopsis:

#include <sys/pci.h>
int _CA_PCI_Read_Config_Byte( unsigned busnum,
                              unsigned devfuncname,
                              unsigned offset,
                              unsigned cnt,
                              char *bufptr );

Description:

This function reads the specified number of bytes from the configuration space of the given device or function.

The arguments are as follows:

busnum

the bus number

devfuncname

the name of the device or function

offset

the register offset into the configuration space, in the range 0 through 255

cnt

the number of bytes to read

bufptr

a pointer to a buffer where the requested bytes are placed

Returns:

PCI_SUCCESS

the device or function was found

PCI_BAD_REGISTER_NUMBER

an invalid register offset was given

Examples:

See _CA_PCI_Find_Device().

Classification:

Intel

Caveats:

When you use the _CA_PCI_... functions:

• Your program must be linked for privity level 1, and the process must be run by the superuser (root) or a setuid program that's owned by the superuser but started by a regular user. For more information on privity, see the cc -T option or the Linker PRIVILEGE option.
• The stack size must be less than 64K.

See also:

_CA_PCI_BIOS_Present(), _CA_PCI_Find_Class(), _CA_PCI_Find_Device(), _CA_PCI_GenerateSpecialCycle(), _CA_PCI_Read_Config_DWord(), _CA_PCI_Read_Config_Word(), _CA_PCI_Write_Config_Byte(), _CA_PCI_Write_Config_DWord(), _CA_PCI_Write_Config_Word()