BUS_READ_IVAR9
Manipulate bus-specific device instance variables
Usage
#include <sys/param.h>
#include <sys/bus.h>
int
BUS_READ_IVAR(device_t dev, device_t child, int index, uintptr_t *result);
int
BUS_WRITE_IVAR(device_t dev, device_t child, int index, uintptr_t value);
Overview
These two methods manage a bus specific set of instance variables of a child device. The intention is that each different type of bus defines a set of appropriate instance variables (such as ports and irqs for ISA bus etc.)
This information could be given to the child device as a struct but that makes it hard for a bus to add or remove variables without forcing an edit and recompile for all drivers which may not be possible for vendor supplied binary drivers.
Return values
Zero is returned on success, otherwise an appropriate error is returned.
Releases
77 releases since FreeBSD 3.0-RELEASE; the text changed 40 times.