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diff --git a/sbin/fdisk/fdisk.8 b/sbin/fdisk/fdisk.8 new file mode 100644 index 0000000..a43a85a --- /dev/null +++ b/sbin/fdisk/fdisk.8 @@ -0,0 +1,409 @@ +.Dd October 4, 1996 +.Dt FDISK 8 +.\".Os BSD 4 +.Sh NAME +.Nm fdisk +.Nd DOS partition maintenance program +.Sh SYNOPSIS +.Nm +.Op Fl i +.Op Fl u +.Op Fl a +.Op Fl 0123 +.Op Ar disk +.Bl -tag -width time +.Nm fdisk +.Op Fl f Ar configfile +.Op Fl i +.Op Fl v +.Op Fl t +.Op Ar disk +.Sh PROLOGUE +In order for the BIOS to boot the kernel, +certain conventions must be adhered to. +Sector 0 of the disk must contain boot code, +a partition table, +and a magic number. +BIOS partitions can be used to break the disk up into several pieces. +The BIOS brings in sector 0 +(does it really use the code?) +and verifies the magic number. +It then searches the 4 BIOS partitions described by sector 0 +to determine which of them is +.Em active. +This boot then brings in the secondary boot block from the +.Em active +partition and runs it. +Under DOS, +you could have one or more partitions with one +.Em active. +The DOS +.Nm +program can be used to divide space on the disk into partitions and set one +.Em active. +.Sh DESCRIPTION +.Pp +The FreeBSD program +.Nm +serves a similar purpose to the DOS program. The first form is used to +display partition information or to interactively edit the partition +table. The second is used to write a partition table using a +.Ar configfile +and is designed to be used by other scripts/programs. +.Pp +Options are: +.It Fl u +Is used for updating (editing) sector 0 of the disk. Ignored if +.Fl f +is given. +.It Fl i +Initializes sector 0 of the disk. This implies +.Fl u , +unless +.Fl f +is given. +.It Fl a +Change the active partition only. Ignored if +.Fl f +is given. +.It Fl 0123 +Operate on a single fdisk entry only. Ignored if +.Fl f +is given. +.It Fl f Ar configfile +Set partition values using the file +.Ar configfile . +The +.Ar configfile +always modifies existing partitions, unless +.Fl i +is also given, in which case all existing partitions are deleted (marked +as "unused") before the +.Ar configfile +is read. The +.Ar configfile +can be "-", in which case +.Ar stdin +is read. See +.Em CONFIGURATION FILE , +below, for file syntax. +.Pp +.Em WARNING: +when +.Fl f +is used, you are not asked if you really want to write the partition +table (as you are in the interactive mode). Use with caution! +.It Fl t +Test mode; do not write partition values. Generally used with the +.Fl f +option to see what would be written to the partition table. Implies +.Fl v . +.It Fl v +Be verbose. When +.Fl f +is used, +.Nm +prints out the partition table that is written to the disk. +.El +.Pp +The final disk name can be provided as a +.Sq bare +disk name only, e.g. +.Ql sd0 , +or as a fully qualified device node under +.Pa /dev . +If omitted, the disks +.Ql wd0 , +.Ql sd0 , +and +.Ql od0 +are being searched in that order, until one is +being found responding. +.Pp +When called with no arguments, it prints the sector 0 partition table. +An example follows: + +.Bd -literal + ******* Working on device /dev/rwd0 ******* + parameters extracted from in-core disklabel are: + cylinders=769 heads=15 sectors/track=33 (495 blks/cyl) + + parameters to be used for BIOS calculations are: + cylinders=769 heads=15 sectors/track=33 (495 blks/cyl) + + Warning: BIOS sector numbering starts with sector 1 + Information from DOS bootblock is: + The data for partition 0 is: + sysid 165,(FreeBSD/NetBSD/386BSD) + start 495, size 380160 (185 Meg), flag 0 + beg: cyl 1/ sector 1/ head 0; + end: cyl 768/ sector 33/ head 14 + The data for partition 1 is: + sysid 164,(unknown) + start 378180, size 2475 (1 Meg), flag 0 + beg: cyl 764/ sector 1/ head 0; + end: cyl 768/ sector 33/ head 14 + The data for partition 2 is: + <UNUSED> + The data for partition 3 is: + sysid 99,(ISC UNIX, other System V/386, GNU HURD or Mach) + start 380656, size 224234 (109 Meg), flag 80 + beg: cyl 769/ sector 2/ head 0; + end: cyl 197/ sector 33/ head 14 +.Ed +.Pp +The disk is divided into three partitions that happen to fill the disk. +The second partition overlaps the end of the first. +(Used for debugging purposes) +.Bl -tag -width "cyl, sector and head" +.It Em "sysid" +is used to label the partition. FreeBSD reserves the +magic number 165 decimal (A5 in hex). +.It Em "start and size" +fields provide the start address +and size of a partition in sectors. +.It Em "flag 80" +specifies that this is the active partition. +.It Em "cyl, sector and head" +fields are used to specify the beginning address +and end address for the partition. +.It Em "Note:" +these numbers are calculated using BIOS's understanding of the disk geometry +and saved in the bootblock. +.El +.Pp +The flags +.Fl i +or +.Fl u +are used to indicate that the partition data is to be updated, unless the +.Fl f +option is used. If the +.Fl f +option is not used, the +.Nm +program will enter a conversational mode. +This mode is designed not to change any data unless you explicitly tell it to. +.Nm +selects defaults for its questions to guarantee the above behavior. +.Pp +It displays each partition +and ask if you want to edit it. +If you say yes, +it will step through each field showing the old value +and asking for a new one. +When you are done with a partition, +.Nm +will display it and ask if it is correct. +.Nm +will then proceed to the next entry. +.Pp +Getting the +.Em cyl, sector, +and +.Em head +fields correct is tricky. +So by default, +they will be calculated for you; +you can specify them if you choose. +.Pp +After all the partitions are processed, +you are given the option to change the +.Em active +partition. +Finally, +when the all the data for the first sector has been accumulated, +you are asked if you really want to rewrite sector 0. +Only if you answer yes, +will the data be written to disk. +.Pp +The difference between the +.Fl u +flag and +.Fl i +flag is that +the +.Fl u +flag just edits the fields as they appear on the disk. +While the +.Fl i +flag is used to "initialize" sector 0; +it will setup the last BIOS partition to use the whole disk for FreeBSD; +and make it active. +.Sh NOTES +.Pp +The automatic calculation of starting cylinder etc. uses +a set of figures that represent what the BIOS thinks is the +geometry of the drive. +These figures are by default taken from the incore disklabel, +but the program initially gives you an opportunity to change them. +This allows the user to create a bootblock that can work with drives +that use geometry translation under the BIOS. +.Pp +If you hand craft your disk layout, +please make sure that the FreeBSD partition starts on a cylinder boundary. +A number of decisions made later may assume this. +(This might not be necessary later.) +.Pp +Editing an existing partition will most likely cause you to +lose all the data in that partition. +.Pp +You should run this program interactively once or twice to see how it +works. This is completely safe as long as you answer the last question +in the negative. There are subtleties that the program detects that are +not fully explained in this manual page. +.Sh CONFIGURATION FILE +.Pp +When the +.Fl f +option is given, a disk's partition table can be written using values +from a +.Ar configfile . +The syntax of this file is very simple. Each line is either a comment or +a specification, and whitespace (except for newlines) are ignored: +.Bl -tag -width Ds +.It Xo +.Ic # +.No Ar comment ... +.Xc +Lines beginning with a "#" are comments and are ignored. +.It Xo +.Ic g +.No Ar spec1 +.No Ar spec2 +.No Ar spec3 +.Xc +Set the BIOS geometry used in partition calculations. There must be +three values specfied, with a letter preceding each number: +.Bl -tag -width Ds +.Sm off +.It Cm c No Ar num +.Sm on +Set the number of cylinders to +.Ar num . +.Sm off +.It Cm h No Ar num +.Sm on +Set the number of heads to +.Ar num . +.Sm off +.It Cm s No Ar num +.Sm on +Set the number of sectors/track to +.Ar num . +.El +.Pp +These specs can occur in any order, as the leading letter determines +which value is which; however, all three must be specified. +.Pp +This line must occur before any lines that specify partition +information. +.Pp +It is an error if the following is not true: +.Pp +.nf + 1 <= number of cylinders + 1 <= number of heads <= 256 + 1 <= number of sectors/track < 64 +.fi +.Pp +The number of cylinders should be less than or equal to 1024, but this +is not enforced, although a warning will be output. Note that bootable +FreeBSD partitions (the "/" filesystem) must lie completely within the +first 1024 cylinders; if this is not true, booting may fail. +Non-bootable partitions do not have this restriction. +.Pp +Example (all of these are equivalent), for a disk with 1019 cylinders, +39 heads, and 63 sectors: +.Pp +.nf + g c1019 h39 s63 + g h39 c1019 s63 + g s63 h39 c1019 +.fi +.It Xo +.Ic p +.No Ar partition +.No Ar type +.No Ar start +.No Ar length +.Xc +Set the partition given by +.Ar partition +(0-3) to type +.Ar type , +starting at sector +.Ar start +for +.Ar length +sectors. +.Pp +Only those partitions explicitly mentioned by these lines are modified; +any partition not referenced by a "p" line will not be modified. +However, if an invalid partition table is present, or the +.Fl i +option is specified, all existing partition entries will be cleared +(marked as unused), and these "p" lines will have to be used to +explicitly set partition information. If multiple partitions need to be +set, multiple "p" lines must be specified; one for each partition. +.Pp +These partition lines must occur after any geometry specification lines, +if one is present. +.Pp +The +.Ar type +is 165 for FreeBSD partitions. Specifying a partition type of zero is +the same as clearing the partition and marking it as unused; however, +dummy values (such as "0") must still be specified for +.Ar start +and +.Ar length . +.Pp +Note: the start offset will be rounded upwards to a head boundary if +necessary, and the end offset will be rounded downwards to a cylinder +boundary if necessary. +.Pp +Example: to clear partition 3 and mark it as unused: +.Pp +.nf + p 3 0 0 0 +.fi +.Pp +Example: to set partition 0 to a FreeBSD partition, starting at sector 1 +for 2503871 sectors (note: these numbers will be rounded upwards and +downwards to correspond to head and cylinder boundaries): +.Pp +.nf + p 0 165 1 2503871 +.fi +.It Xo +.Ic a +.No Ar partition +.Xc +Make +.Ar partition +the active partition. Can occur anywhere in the config file, but only +one must be present. +.Pp +Example: to make partition 0 the active partition: +.Pp +.nf + a 0 +.fi + +.El +.Pp +.Sh SEE ALSO +.Xr disklabel 8 +.Sh BUGS +The entire program should be made more user-friendly. +.Pp +Throughout this man page, the term +.Sq partition +is used where it should actually be +.Sq slice , +in order to conform with the terms used elsewhere. +.Pp +You cannot use this command to completely dedicate a disk to FreeBSD. The +.Xr disklabel 8 +command must be used for this. |
