PATH_TO_INST(5) Standards, Environments, and Macros PATH_TO_INST(5)


path_to_inst - device instance number file




/etc/path_to_inst records mappings of physical device names to instance

The instance number of a device is encoded in its minor number, and is
the way that a device driver determines which of the possible devices
that it may drive is referred to by a given special file.

In order to keep instance numbers persistent across reboots, the system
records them in /etc/path_to_inst.

This file is read only at boot time, and is updated by add_drv(8) and

Note that it is generally not necessary for the system administrator to
change this file, as the system will maintain it.

The system administrator can change the assignment of instance numbers by
editing this file and doing a reconfiguration reboot. However, any
changes made in this file will be lost if add_drv(8) or devfsadm(8) is
run before the system is rebooted.

Each instance entry is a single line of the form:

"physical name" instance number "driver binding name"


physical name
is the absolute physical pathname of a device.
This pathname must be enclosed in double quotes.

instance number
is a decimal or hexadecimal number.

driver binding name
is the name used to determine the driver for the
device. This name may be a driver alias or a
driver name. The driver binding name must be
enclosed in double quotes.


Example 1: Sample path_to_inst Entries

Here are some sample path_to_inst entries:

"/iommu@f,e0000000" 0 "iommu"
"/iommu@f,e0000000/sbus@f,e0001000" 0 "sbus"
"/iommu@f,e0000000/sbus@f,e0001000/sbusmem@e,0" 14 "sbusmem"
"/iommu@f,e0000000/sbus@f,e0001000/sbusmem@f,0" 15 "sbusmem"
"/iommu@f,e0000000/sbus@f,e0001000/ledma@f,400010" 0 "ledma"
"/obio/serial@0,100000" 0 "zs"
"/SUNW,sx@f,80000000" 0 "SUNW,sx"


Mapping of physical device names to instance


add_drv(8), boot(8), devfsadm(8), mknod(8)


If the file is removed the system may not be bootable (as it may rely on
information found in this file to find the root, usr or swap device). If
it does successfully boot, it will regenerate the file, but after
rebooting devices may end up having different minor numbers than they did
before, and special files created via mknod(8) may refer to different
devices than expected.

For the same reasons, changes should not be made to this file without
careful consideration.


This document does not constitute an API. path_to_inst may not exist or
may have a different content or interpretation in a future release. The
existence of this notice does not imply that any other documentation that
lacks this notice constitutes an API.

May 18, 2007 PATH_TO_INST(5)