1REBOOT(8) 386BSD System Manager's Manual REBOOT(8) 2 3NNAAMMEE 4 rreebboooott - UNIX bootstrapping procedures 5 6SSYYNNOOPPSSIISS 7 rreebboooott [--nn] [--qq] 8 9DDEESSCCRRIIPPTTIIOONN 10 UNIX, an ordinary executable file, is placed into memory by bootstrap at 11 location absolute zero, and entered at the executable's entry point 12 (_a__e_n_t_r_y). Upon startup, the system reorganizes memory to suit the needs 13 of the hardware configuration found, thus it is not designed to be 14 restartable without being reloaded on reboot. Each time it is to be 15 bootstrapped, it must be reloaded, usually from a disk file. 16 17 RReebboooottiinngg aa rruunnnniinngg ssyysstteemm. When a UNIX is running and a reboot is 18 desired, shutdown(8) is normally used. If there are no users then rreebboooott 19 can be used. Reboot causes the disks to be synced and allows the system 20 to perform other shutdown activities such as resynchronizing hardware 21 time-of-day clocks. A multi-user reboot (as described below) is then 22 initiated. This causes a system to be booted and an automatic disk check 23 to be performed. If all this succeeds without incident, the system is 24 then brought up for many users. 25 26 Options to reboot are: 27 28 --nn option avoids the sync. It can be used if a disk or the 29 processor is on fire. 30 31 --qq reboots quickly and ungracefully, without shutting down running 32 processes first. 33 34 RReebboooott normally logs the reboot using syslog(8) and places a shutdown 35 record in the login accounting file /_v_a_r/_l_o_g/_w_t_m_p. These actions are 36 inhibited if the --nn or --qq options are present. 37 38 PPoowweerr ffaaiill aanndd ccrraasshh rreeccoovveerryy.. Normally, the system will reboot itself at 39 power-up or after crashes. An automatic consistency check of the file 40 systems will be performed as described in fsck(8). and unless this 41 fails, the system will resume multi-user operations. 42 43 CCoolldd ssttaarrttss. The 386 PC AT clones attempt to boot the floppy disk drive A 44 (otherwise known as drive 0) first, and failing that, attempt to boot the 45 hard disk C (otherwise known as hard disk controller 1, drive 0). The 46 automatic boot will attempt to load _v_m_u_n_i_x from partition A of either the 47 floppy or the hard disk. This boot may be aborted by typing any character 48 on the keyboard repeatedly (four or five times at least) during the 49 operating system load phase, after which the bootstrap will prompt for 50 the file that you wish to load instead. 51 52 One exception to this is the `d' key, which will not abort the load but 53 instead silently force the DEBUG boot flags. The boot flags for an 54 autoboot are 0, and 3 for the successive boot after an aborted autoboot 55 sequence. No other provison is made for setting boot flags (yet). A 56 specific device or bootstrap file may be used; for example, 57 58 The file specifications used for the boostrap when loaded with the 59 ``askme'' flag (e.g. an aborted autoboot) are of the form: 60 61 device unit partition: 62 63 where _d_e_v_i_c_e is the type of the device, assumed to be on the ISA bus, to 64 be searched, _u_n_i_t is the unit number of the disk or tape, and _p_a_r_t_i_t_i_o_n 65 is the disk partition or tape file number. Normal line editing 66 characters can be used when typing the file specification. The following 67 list of supported devices may vary from installation to installation: 68 69 wd ST506, IDE, ESDI, RLL disks on a WD100[2367] or lookalike 70 controller 71 fd 5 1/4" or 3 1/2" High density floppies 72 73 For example, to boot from a file system which starts at cylinder 0 of 74 unit 0 of an IDE disk, type ``wd0a:vmunix'' to the boot prompt; 75 ``fd0a:vmunix'' would specify a 3 1/2" floppy drive 0 . 76 77 In an emergency, the bootstrap methods described in the paper _I_n_s_t_a_l_l_i_n_g 78 _a_n_d _O_p_e_r_a_t_i_n_g _4._3 _B_S_D-_R_e_n_o _U_N_I_X _o_n _t_h_e _A_T/_3_8_6 can be used to boot from a 79 distribution tape. 80 81FFIILLEESS 82 /vmunix system code 83 /boot system bootstrap 84 85SSEEEE AALLSSOO 86 crash(8), disklabel(8), fsck(8), halt(8), init(8), rc(8), 87 shutdown(8), syslogd(8) 88 89BBUUGGSS 90 The disklabel format used by this version of BSD UNIX is quite different 91 from that of other architectures. 92 93BSD Experimental April 25, 1991 2 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133