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$FreeBSD: stable/10/share/man/man4/geom_uncompress.4 266220 2014-05-16 14:28:55Z loos $
.Dd January 9, 2014 .Dt GEOM_UNCOMPRESS 4 .Os .Sh NAME .Nm geom_uncompress .Nd "GEOM based compressed disk images" .Sh SYNOPSIS To compile this driver into the kernel, place the following line in your kernel configuration file: d -ragged -offset indent .Cd "options GEOM_UNCOMPRESS" .Ed
p Alternatively, to load the driver as a module at boot time, place the following line in .Xr loader.conf 5 : d -literal -offset indent geom_uncompress_load="YES" .Ed .Sh DESCRIPTION The .Nm framework provides support for compressed read only disk images. This allows significant storage savings at the expense of a little CPU time on each read. Data written in the GEOM label area allows .Nm to detect compressed images which have been created with .Xr mkulzma 8 or .Xr mkuzip 8 and presented to the kernel as a logical disk device via .Xr md 4 . .Nm creates a unique
a md#.uncompress device for each image.
p The .Nm device is subsequently used by the .Fx kernel to access the disk images. The .Nm driver does not allow write operations to the underlying disk image. To check which .Xr md 4 devices match a given .Nm device: d -literal -offset indent # geom uncompress list Geom name: md0.uncompress Providers: 1. Name: md0.uncompress Mediasize: 52428800 (50M) Sectorsize: 512 Mode: r1w0e0 Consumers: 1. Name: md0 Mediasize: 20864000 (20M) Sectorsize: 512 Mode: r1w0e0 .Ed .Sh SEE ALSO .Xr GEOM 4 , .Xr md 4 , .Xr geom 8 , .Xr mkulzma 8 , .Xr mkuzip 8 .Sh AUTHORS .An -nosplit The .Nm driver was written by .An "Maxim Sobolev" Aq sobomax@FreeBSD.org and .An "Aleksandr Rybalko" Aq ray@FreeBSD.org . This manual page was written by .An "Luiz Otavio O Souza" Aq loos@FreeBSD.org .