diff options
Diffstat (limited to 'sbin/fdisk/fdisk.8')
| -rw-r--r-- | sbin/fdisk/fdisk.8 | 173 |
1 files changed, 173 insertions, 0 deletions
diff --git a/sbin/fdisk/fdisk.8 b/sbin/fdisk/fdisk.8 new file mode 100644 index 00000000000..6d3a37b4c9b --- /dev/null +++ b/sbin/fdisk/fdisk.8 @@ -0,0 +1,173 @@ +.\" $NetBSD: fdisk.8,v 1.8 1995/03/18 14:55:34 cgd Exp $ +.\" +.Dd April 4, 1993 +.Dt FDISK 8 +.\" .Os BSD 4 +.Sh NAME +.Nm fdisk +.Nd DOS partition maintenance program +.Sh SYNOPSIS +.Nm +.Op Fl aiu +.Op Ar device +.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, verifies the magic number, and begins +executing the code at the first byte. +This code is turn searches the DOS partition table for an `active' +partition. +If one is found, the boot block from that partition is loaded and replaces +the original boot block. +Under DOS, you could have one or more partitions with one active. +The DOS +.Nm +program can be used to divide space on the disk into partitions and set +one active. +.Pp +The NetBSD program +.Nm +serves a similar purpose to the DOS program. +When called with no arguments, it prints the sector 0 partition table. +An example follows: +.Bd -literal + ******* Working on device /dev/rwd0d ******* + parameters extracted from in-core disklabel are: + cylinders=769 heads=15 sectors/track=33 (495 sectors/cylinder) + + parameters to be used for BIOS calculations are: + cylinders=769 heads=15 sectors/track=33 (495 sectors/cylinder) + + Warning: BIOS sector numbering starts with sector 1 + Information from DOS bootblock is: + The data for partition 0 is: + sysid 165 (NetBSD) + start 495, size 380160 (185 MB), flag 0 + beg: cylinder 1, head 0, sector 1 + end: cylinder 768, head 14, sector 33 + The data for partition 1 is: + sysid 164 (unknown) + start 378180, size 2475 (1 MB), flag 0 + beg: cylinder 764, head 0, sector 1 + end: cylinder 768, head 14, sector 33 + 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 MB), flag 80 + beg: cylinder 769, head 0, sector 2 + end: cylinder 197, head 14, sector 33 +.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. NetBSD 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. +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 that behavior. +.Pp +It displays each partition and asks if you want to edit it. +If you reply affirmatively, +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 the information again and ask if it is correct. +.Nm +will then procede 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. +To change only the +.Em active +partition, you can use the +.Fl a +flag instead. +.Pp +Finally, +when the all the data for the first sector has been accumulated, +.Nm +will ask if you really want to rewrite sector 0. +Only if you reply affirmatively to this question will +.Nm +write anything to the 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. +The +.Fl i +flag instructs +.Nm +to start by making the first 3 partitions empty, setting the last partition +to use the whole disk for NetBSD, and marking the last partition active. +.Sh NOTES +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 +.Nm +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 NetBSD partition starts on a cylinder boundary. +(This restriction may be changed in the future.) +.Pp +Editing an existing partition is risky, and may 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. +.Sh SEE ALSO +.Xr disklabel 8 +.Sh BUGS +There are subtleties that the program detects that are not explained in +this manual page. |