2 menu "Character Devices"
9 bool "Virtual serial line"
11 The User-Mode Linux environment allows you to create virtual serial
12 lines on the UML that are usually made to show up on the host as
15 See <http://user-mode-linux.sourceforge.net/input.html> for more
16 information and command line examples of how to use this facility.
18 Unless you have a specific reason for disabling this, say Y.
21 bool "file descriptor channel support"
23 This option enables support for attaching UML consoles and serial
24 lines to already set up file descriptors. Generally, the main
25 console is attached to file descriptors 0 and 1 (stdin and stdout),
26 so it would be wise to leave this enabled unless you intend to
27 attach it to some other host device.
30 bool "null channel support"
32 This option enables support for attaching UML consoles and serial
33 lines to a device similar to /dev/null. Data written to it disappears
34 and there is never any data to be read.
37 bool "port channel support"
39 This option enables support for attaching UML consoles and serial
40 lines to host portals. They may be accessed with 'telnet <host>
41 <port number>'. Any number of consoles and serial lines may be
42 attached to a single portal, although what UML device you get when
43 you telnet to that portal will be unpredictable.
44 It is safe to say 'Y' here.
47 bool "pty channel support"
49 This option enables support for attaching UML consoles and serial
50 lines to host pseudo-terminals. Access to both traditional
51 pseudo-terminals (/dev/pty*) and pts pseudo-terminals are controlled
52 with this option. The assignment of UML devices to host devices
53 will be announced in the kernel message log.
54 It is safe to say 'Y' here.
57 bool "tty channel support"
59 This option enables support for attaching UML consoles and serial
60 lines to host terminals. Access to both virtual consoles
61 (/dev/tty*) and the slave side of pseudo-terminals (/dev/ttyp* and
62 /dev/pts/*) are controlled by this option.
63 It is safe to say 'Y' here.
66 bool "xterm channel support"
68 This option enables support for attaching UML consoles and serial
69 lines to xterms. Each UML device so assigned will be brought up in
71 If you disable this option, then CONFIG_PT_PROXY will be disabled as
72 well, since UML's gdb currently requires an xterm.
73 It is safe to say 'Y' here.
76 string "Default main console channel initialization"
79 This is the string describing the channel to which the main console
80 will be attached by default. This value can be overridden from the
81 command line. The default value is "fd:0,fd:1", which attaches the
82 main console to stdin and stdout.
83 It is safe to leave this unchanged.
86 string "Default console channel initialization"
89 This is the string describing the channel to which all consoles
90 except the main console will be attached by default. This value can
91 be overridden from the command line. The default value is "xterm",
92 which brings them up in xterms.
93 It is safe to leave this unchanged, although you may wish to change
94 this if you expect the UML that you build to be run in environments
95 which don't have X or xterm available.
98 string "Default serial line channel initialization"
101 This is the string describing the channel to which the serial lines
102 will be attached by default. This value can be overridden from the
103 command line. The default value is "pty", which attaches them to
104 traditional pseudo-terminals.
105 It is safe to leave this unchanged, although you may wish to change
106 this if you expect the UML that you build to be run in environments
107 which don't have a set of /dev/pty* devices.
110 bool "Unix98 PTY support"
112 A pseudo terminal (PTY) is a software device consisting of two
113 halves: a master and a slave. The slave device behaves identical to
114 a physical terminal; the master device is used by a process to
115 read data from and write data to the slave, thereby emulating a
116 terminal. Typical programs for the master side are telnet servers
119 Linux has traditionally used the BSD-like names /dev/ptyxx for
120 masters and /dev/ttyxx for slaves of pseudo terminals. This scheme
121 has a number of problems. The GNU C library glibc 2.1 and later,
122 however, supports the Unix98 naming standard: in order to acquire a
123 pseudo terminal, a process opens /dev/ptmx; the number of the pseudo
124 terminal is then made available to the process and the pseudo
125 terminal slave can be accessed as /dev/pts/<number>. What was
126 traditionally /dev/ttyp2 will then be /dev/pts/2, for example.
128 All modern Linux systems use the Unix98 ptys. Say Y unless
129 you're on an embedded system and want to conserve memory.
132 bool "Legacy (BSD) PTY support"
135 A pseudo terminal (PTY) is a software device consisting of two
136 halves: a master and a slave. The slave device behaves identical to
137 a physical terminal; the master device is used by a process to
138 read data from and write data to the slave, thereby emulating a
139 terminal. Typical programs for the master side are telnet servers
142 Linux has traditionally used the BSD-like names /dev/ptyxx
143 for masters and /dev/ttyxx for slaves of pseudo
144 terminals. This scheme has a number of problems, including
145 security. This option enables these legacy devices; on most
146 systems, it is safe to say N.
149 config LEGACY_PTY_COUNT
150 int "Maximum number of legacy PTY in use"
151 depends on LEGACY_PTYS
154 The maximum number of legacy PTYs that can be used at any one time.
155 The default is 256, and should be more than enough. Embedded
156 systems may want to reduce this to save memory.
158 When not in use, each legacy PTY occupies 12 bytes on 32-bit
159 architectures and 24 bytes on 64-bit architectures.
162 bool "Watchdog Timer Support"
164 config WATCHDOG_NOWAYOUT
165 bool "Disable watchdog shutdown on close"
169 tristate "Software Watchdog"
173 tristate "UML watchdog"
177 tristate "Sound support"
179 This option enables UML sound support. If enabled, it will pull in
180 soundcore and the UML hostaudio relay, which acts as a intermediary
181 between the host's dsp and mixer devices and the UML sound system.
182 It is safe to say 'Y' here.