5 bool "Virtual block device"
7 The User-Mode Linux port includes a driver called UBD which will let
8 you access arbitrary files on the host computer as block devices.
9 Unless you know that you do not need such virtual block devices say
12 config BLK_DEV_UBD_SYNC
13 bool "Always do synchronous disk IO for UBD"
14 depends on BLK_DEV_UBD
16 Writes to the virtual block device are not immediately written to the
17 host's disk; this may cause problems if, for example, the
18 User-Mode Linux 'Virtual Machine' uses a journalling filesystem and
19 the host computer crashes.
21 Synchronous operation (i.e. always writing data to the host's disk
22 immediately) is configurable on a per-UBD basis by using a special
23 kernel command line option. Alternatively, you can say Y here to
24 turn on synchronous operation by default for all block devices.
26 If you're running a journalling file system (like reiserfs, for
27 example) in your virtual machine, you will want to say Y here. If
28 you care for the safety of the data in your virtual machine, Y is a
29 wise choice too. In all other cases (for example, if you're just
30 playing around with User-Mode Linux) you can choose N.
32 # Turn this back on when the driver actually works
35 # tristate "COW block device"
37 # This is a layered driver which sits above two other block devices.
38 # One is read-only, and the other is a read-write layer which stores
39 # all changes. This provides the illusion that the read-only layer
40 # can be mounted read-write and changed.
42 config BLK_DEV_COW_COMMON
44 default BLK_DEV_COW || BLK_DEV_UBD
47 tristate "Loopback device support"
50 tristate "Network block device support"
54 tristate "RAM disk support"
56 config BLK_DEV_RAM_SIZE
57 int "Default RAM disk size"
58 depends on BLK_DEV_RAM
62 bool "Initial RAM disk (initrd) support"
63 depends on BLK_DEV_RAM=y
66 tristate "Example IO memory driver"
68 The User-Mode Linux port can provide support for IO Memory
69 emulation with this option. This allows a host file to be
70 specified as an I/O region on the kernel command line. That file
71 will be mapped into UML's kernel address space where a driver can
72 locate it and do whatever it wants with the memory, including
73 providing an interface to it for UML processes to use.
75 For more information, see
76 <http://user-mode-linux.sourceforge.net/iomem.html>.
78 If you'd like to be able to provide a simulated IO port space for
79 User-Mode Linux processes, say Y. If unsure, say N.