o Fix a typo.
o Describe the file formats mkimg can create.
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@ -24,7 +24,7 @@
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.\"
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.\" $FreeBSD$
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.\"
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.Dd February 22, 2015
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.Dd August 7, 2015
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.Dt MKIMG 1
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.Os
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.Sh NAME
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@ -141,7 +141,7 @@ utility will create images that are identical.
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.Pp
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A set of long options exist to query about the
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.Nm
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utilty itself.
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utility itself.
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Options in this set should be given by themselves because the
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.Nm
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utility exits immediately after providing the requested information.
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@ -165,6 +165,85 @@ run the
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.Nm
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utility without any arguments.
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This will print a usage message with all the necessary details.
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.Sh DISK FORMATS
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The
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.Nm
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utility supports a number of output file formats.
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A short description of these is given below.
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.Ss QCOW and QCOW2
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QCOW stands for "QEMU Copy On Write".
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It's a sparse file format akin to VHD and VMDK and QCOW represents the
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first version.
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QCOW2 represents version 2 of the file format.
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Version 2 is not backward compatible with version 1 and adds support for
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snapshots among other things.
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The QCOW file formats are natively supported by QEMU and Xen.
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To write QCOW, specify
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.Fl f Ar qcow
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on the command line.
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To write version 2 QCOW, specify
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.Fl f Ar qcow2
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on the command line.
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The preferred file extension is ".qcow" iand ".qcow2" for QCOW and QCOW2
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(resp.), but ".qcow" is sometimes used for version 2 files as well.
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.Ss RAW file format
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This file format is a sector by sector representation of an actual disk.
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There is no extra information that describes or relates to the format
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itself. The size of the file is the size of the (virtual) disk.
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This file format is suitable for being copyied onto a disk with utilities
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like
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.Nm dd .
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To write a raw disk file, either omit the
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.Fl f
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option, or specify
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.Fl f Ar raw
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on the command line.
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The preferred file extension is one of ".img" or ".raw", but there's no
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real convention for it.
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.Ss Dynamic VHD and Fixed VHD
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Microsoft's "Virtual Hard Disk" file formats.
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The dynamic format is a sparse format akin to QCOW and VMDK.
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The fixed format is effectively a raw format with a footer appended to the
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file and as such it's often indistinguishable from the raw format.
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The fixed file format has been added to support Microsoft's Azure platform
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and due to inconsistencies in interpretation of the footer is not compatible
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with utilities like
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.Nm qemu
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when it is specifically instructed to interpreted the file as a VHD file.
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By default
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.Nm qemu
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will treat the file as a raw disk file, which mostly works fine.
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To have
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.Nm
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create a dynamic VHD file, specify
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.Fl f Ar vhd
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on the command line.
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To create a fixed VHD file for use by Azure, specify
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.Fl f Ar vhdf
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on the command line.
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The preferred file extension is ".vhd".
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.Ss VMDK
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VMware's "Virtual Machine Disk" file format.
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It's a sparse file format akin to QCOW and VHD and supported by many
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virtualization solutions.
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To create a VMDK file, specify
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.Fl f Ar vmdk
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on the command line.
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The preferred file extension is ".vmdk".
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.Pp
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Not all virtualization solutions support all file formats, but often those
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virtualization environments have utilities to convert from one format to
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another.
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Note however that conversion may require that the virtual disk size is
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changed to match the constraints of the output format and this may invalidate
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the contents of the disk image.
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For example, the GUID Partition Table (GPT) scheme has a header in the last
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sector on the disk.
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When changing the disk size, the GPT must be changed so that the last header
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is moved accordingly.
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This is typically not part of the conversion process.
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If possible, use an output format specifically for the environment in which
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the file is intended to be used.
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.Sh ENVIRONMENT
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.Bl -tag -width "TMPDIR" -compact
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.It Ev TMPDIR
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@ -235,6 +314,7 @@ utility supports assigning labels to the partitions specified.
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In the following example the file system partition is labeled as 'backup':
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.Dl % mkimg -s gpt -p freebsd-ufs/backup:=file-system.ufs -o gpt.img
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.Sh SEE ALSO
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.Xr dd 1 ,
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.Xr gpart 8 ,
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.Xr makefs 8 ,
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.Xr mdconfig 8 ,
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