ioconfig(4)ioconfig(4)NAMEioconfig - ioconfig entry format
The file is used to retain information on a system's I/O configuration
across reboots. It contains two types of information:
· Mappings of dynamically allocated major numbers to drivers.
· Mappings of instance numbers to hardware paths.
At boot time this file is read and the information is stored in the
kernel data structure. The file is created by at install time and is
modified by and when devices are added or removed (see insf(1M),
rmsf(1M), and ioscan(1M)). The only purpose of the file to maintain
configuration information when the system is not running. While the
system is running, all accesses are made directly to the kernel struc‐
ture, although any tools that change the kernel structures must also
There will be two copies of maintained: and A second copy is placed in
because NFS diskless clients are not guaranteed to have a reliable
directory at boot time.
The file begins with the magic number.
Following the magic number is an array of structures, which logically
form a tree structure defining the connectivity of the various levels
of software modules and managers, the device class and hardware address
of each element, and the logical unit associated with each leaf node.
The root of the tree is array element 0.
Each contains the following fields as defined in
The definitions of each element are as follows:
Each record must have a character string as its first entry
which is used to identify the record type. The default
record is the If the string begins with an underscore charac‐
ter then it is one of the variants.
This is the default record entry for the ioconfig file.
The must begin with an underscore character to distinguish
record from other record type.
The element is a structure that contains following elements.
This record stores information about major numbers dynamically assigned
to drivers. It is used to allow major number assignments to
persist across boots. The must begin with (underscore) char‐
acter to distinguish record from other record type.
The contains following elements.
was developed by HP.
insf(1M), ioinit(1M), ioscan(1M), rmsf(1M), magic(4).