NAME

reboot − bootstrapping procedures

SYNOPSIS

/etc/reboot [ −n ] [ −q ]

DESCRIPTION

IBM/4.3 starts by placing the kernel in memory at location zero and transferring to the entry point.  Since the system is not re-enterable, it is necessary to read the kernel in from disk or tape each time it is to be loaded. 

Rebooting a running system.  When IBM/4.3 is running and multiple users are logged in, shutdown(8) is normally used to perform a reboot. If there are no users, /etc/reboot can be used.

Reboot causes the disks to be synced and allows the system to perform other shutdown activities such as resynchronizing the hardware time-of-day clock.  A reboot is then started, as described below.  By default, the system boots and the disks are automatically checked.  If all this succeeds without incident, the system comes up for multiple users. 

Options to reboot are:

−n Do not perform the sync.  Use this option if a disk or the processor is on fire. 

−q Reboot quickly and ungracefully, without shutting down running processes first. 

Reboot normally logs the reboot using syslog(8) and places a shutdown record in the login accounting file /usr/adm/wtmp.  These actions are inhibited if the −n or −q options are present. 

Power fail and crash recovery.  Normally, the system will reboot itself at power-up or after crashes.  To force a reboot, simultaneously press and hold the keys labeled <Ctrl>, <Alt> and <Pause>.  If all else fails, turn the machine off, wait at least 60 seconds for the disks to stop spinning, and turn it back on. 

Boot procedure.  After performing diagnostic tests, the system ROM looks for a bootstrap record, searching (in order, and only if present) fd0, fd1, hd0, hd1, and hd2.  It loops until it finds one.  Normally, the bootstrap record reads the boot program from diskette or hard disk.  The boot program prompts for the name of the system to be loaded; the default is hd(0,0)vmunix and takes effect if nothing is typed within about 30 seconds.  (Typing a carriage return will also choose the default.)  By default, the system comes up multi-user, but if a name was entered, the single-user flag is passed to the kernel. 

If the debugger was configured into the kernel, it is entered first, but an implicit “go” will be performed if nothing is entered within about 30 seconds.  A carriage return also performs the “go”. 

FILES

/vmunixsystem code
/bootsystem bootstrap
/usr/mdec/xxbootsector-0 boot block for IBM RT PC, xx is specific disk type
/usr/mdec/bootxxsecond-stage boot for IBM RT PC, xx is generic disk type
/usr/mdec/installbootprogram to install boot blocks on IBM RT PC

SEE ALSO

crash(8R), fsck(8), halt(8), init(8), newfs(8), rc(8), shutdown(8), syslogd(8)

PRPQs 5799-WZQ/5799-PFF: IBM/4.3  —  July 1987