MAC_DEVT_TO_INSTANCE(9F) Kernel Functions for Drivers

NAME

mac_devt_to_instance - return the instance number for the given device
number

SYNOPSIS

#include <sys/mac_provider.h>

int
mac_devt_to_instance(dev_t devt);

INTERFACE LEVEL

illumos DDI specific

PARAMETERS

devt Device number.

DESCRIPTION

The mac_devt_to_instance() function returns the device instance number
associated with the given device number managed by the mac(9E)
framework.

Generally the MAC framework is responsible for managing device instance
mapping and provides a default getinfo(9E) implementation to that
effect.

However, if a driver wants to expose additional device nodes or relies
on some special mapping of device instance to MAC instance then it must
provide its own getinfo(9E) entry point. In that case, the driver can
call the mac_devt_to_instance() function to obtain the MAC specific
instance number and translate it as appropriate to a devinfo instance.

CONTEXT

The mac_devt_to_instance() function should be called from a kernel
context and is generally used during the execution of a driver's
getinfo(9E) entry point.

RETURN VALUES

Upon successful completion, the mac_devt_to_instance() function returns
the instance number associated with the minor. Otherwise -1 is
returned to indicate failure.

SEE ALSO

getinfo(9E), mac(9E), ddi_get_instance(9F), mac_getinfo(9F),
mac_private_minor(9F)

illumos January 30, 2023 illumos