diff --git a/usr.bin/mkimg/mkimg.1 b/usr.bin/mkimg/mkimg.1 index 3b1d63e94136..2738cd898774 100644 --- a/usr.bin/mkimg/mkimg.1 +++ b/usr.bin/mkimg/mkimg.1 @@ -24,7 +24,7 @@ .\" .\" $FreeBSD$ .\" -.Dd February 22, 2015 +.Dd August 7, 2015 .Dt MKIMG 1 .Os .Sh NAME @@ -141,7 +141,7 @@ utility will create images that are identical. .Pp A set of long options exist to query about the .Nm -utilty itself. +utility itself. Options in this set should be given by themselves because the .Nm utility exits immediately after providing the requested information. @@ -165,6 +165,85 @@ run the .Nm utility without any arguments. This will print a usage message with all the necessary details. +.Sh DISK FORMATS +The +.Nm +utility supports a number of output file formats. +A short description of these is given below. +.Ss QCOW and QCOW2 +QCOW stands for "QEMU Copy On Write". +It's a sparse file format akin to VHD and VMDK and QCOW represents the +first version. +QCOW2 represents version 2 of the file format. +Version 2 is not backward compatible with version 1 and adds support for +snapshots among other things. +The QCOW file formats are natively supported by QEMU and Xen. +To write QCOW, specify +.Fl f Ar qcow +on the command line. +To write version 2 QCOW, specify +.Fl f Ar qcow2 +on the command line. +The preferred file extension is ".qcow" iand ".qcow2" for QCOW and QCOW2 +(resp.), but ".qcow" is sometimes used for version 2 files as well. +.Ss RAW file format +This file format is a sector by sector representation of an actual disk. +There is no extra information that describes or relates to the format +itself. The size of the file is the size of the (virtual) disk. +This file format is suitable for being copyied onto a disk with utilities +like +.Nm dd . +To write a raw disk file, either omit the +.Fl f +option, or specify +.Fl f Ar raw +on the command line. +The preferred file extension is one of ".img" or ".raw", but there's no +real convention for it. +.Ss Dynamic VHD and Fixed VHD +Microsoft's "Virtual Hard Disk" file formats. +The dynamic format is a sparse format akin to QCOW and VMDK. +The fixed format is effectively a raw format with a footer appended to the +file and as such it's often indistinguishable from the raw format. +The fixed file format has been added to support Microsoft's Azure platform +and due to inconsistencies in interpretation of the footer is not compatible +with utilities like +.Nm qemu +when it is specifically instructed to interpreted the file as a VHD file. +By default +.Nm qemu +will treat the file as a raw disk file, which mostly works fine. +To have +.Nm +create a dynamic VHD file, specify +.Fl f Ar vhd +on the command line. +To create a fixed VHD file for use by Azure, specify +.Fl f Ar vhdf +on the command line. +The preferred file extension is ".vhd". +.Ss VMDK +VMware's "Virtual Machine Disk" file format. +It's a sparse file format akin to QCOW and VHD and supported by many +virtualization solutions. +To create a VMDK file, specify +.Fl f Ar vmdk +on the command line. +The preferred file extension is ".vmdk". +.Pp +Not all virtualization solutions support all file formats, but often those +virtualization environments have utilities to convert from one format to +another. +Note however that conversion may require that the virtual disk size is +changed to match the constraints of the output format and this may invalidate +the contents of the disk image. +For example, the GUID Partition Table (GPT) scheme has a header in the last +sector on the disk. +When changing the disk size, the GPT must be changed so that the last header +is moved accordingly. +This is typically not part of the conversion process. +If possible, use an output format specifically for the environment in which +the file is intended to be used. .Sh ENVIRONMENT .Bl -tag -width "TMPDIR" -compact .It Ev TMPDIR @@ -235,6 +314,7 @@ utility supports assigning labels to the partitions specified. In the following example the file system partition is labeled as 'backup': .Dl % mkimg -s gpt -p freebsd-ufs/backup:=file-system.ufs -o gpt.img .Sh SEE ALSO +.Xr dd 1 , .Xr gpart 8 , .Xr makefs 8 , .Xr mdconfig 8 ,