ioconfig(4)

NAME

ioconfig — ioconfig entry format

SYNOPSIS

#include <sys/ioparams.h>

DESCRIPTION

The ioconfig 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 io_tree kernel data structure. The ioconfig file is created by insf at install time and is modified by insf, rmsf, and ioscan when devices are added or removed (see insf(1M), rmsf(1M), and ioscan(1M)). The only purpose of the ioconfig file to maintain configuration information when the system is not running. While the system is running, all accesses are made directly to the kernel io_tree structure, although any tools that change the kernel structures must also keep ioconfig consistent.

There will be two copies of ioconfig maintained: /etc/ioconfig and /stand/ioconfig. A second copy is placed in /stand because NFS diskless clients are not guaranteed to have a reliable /etc directory at boot time.

The ioconfig file begins with the ioconfig magic number.

#define  IOCONFIG_MAGIC     0x21224941     /* magic number */ 

Following the magic number is an array of ioconfig_record 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 ioconfig_record contains the following fields as defined in <sys/ioparams.h>:

#define IOCONFIG_FILE   "/etc/ioconfig" 
#define MAX_NAME_LEN          16 

union ioconfig_record { 
    char        rec_name[MAX_NAME_LEN];   /* record type */ 
    ioconfig_t  ioc; 
    dyn_major_t dm; 

} ioconfig_record; 

The definitions of each element are as follows:

rec_name: Each record must have a character string as its first entry which is used to identify the record type. The default record is the ioconfig_t. If the string begins with an underscore (_) character then it is one of the variants.
ioc: This is the default record entry for the ioconfig file. The rec_name must not begin with an underscore (_) character to distinguish record from other record type.

The ioconfig_t element is a structure that contains following elements.

typedef struct ioconfig { 
    char       name[MAX_NAME_LEN];   /* Node name: disc4, scsi_disk */ 
    char       class[MAX_NAME_LEN];  /* Node class: disk, tape, etc */ 
    hw_path_t  hw_path;              /* Path to this node           */ 
    int        instance;             /* Instance number within class*/ 

} ioconfig_t; 

dm: This record stores information about major numbers dynamically assigned to drivers. It is used to allow major number assignments to persist across boots. The rec_name must begin with _ (underscore) character to distinguish record from other record type.

The dyn_major_t contains following elements.

typedef struct dyn_major { 
    char    rec_name[MAX_NAME_LEN];  /* Must be  _DYN_MAJOR" */" 
    char    name[MAX_NAME_LEN];      /* Driver name           */ 
    int     c_major; 
    int     b_major; 
    int     reserved; 

} dyn_major_t; 

AUTHOR

ioconfig was developed by HP.

FILES

/etc/ioconfig
/stand/ioconfig

ioconfig(4)

Technical documentation

» Table of Contents

» Index

NAME

SYNOPSIS

DESCRIPTION

AUTHOR

FILES

SEE ALSO