5 The ultimate goal of this branch is to implement support for opening
6 multiple, different tty devices and simultaneous X and tty frames from
7 a single Emacs session.
12 I'm Károly Lőrentey. My address: lorentey@elte.hu.
14 Patches or suggestions are welcome!
16 Retrieving the latest version of the branch:
18 tla register-archive lorentey@elte.hu--2004 http://lorentey.web.elte.hu/arch/2004/
19 tla get lorentey@elte.hu--2004/emacs--multi-tty--0 <directory>
27 Basic multi-tty support is there; there are some rough edges, but it
28 already seems to be usable. Emacsclient has been extended to support
29 opening a new terminal frame.
31 To try it out, compile Emacs with the following commands
35 ../configure --with-x-toolkit=no --without-x
38 then start up the emacs server (src/emacs, M-x server-start), and then
39 (from a shell prompt on another terminal) start emacsclient with
41 lib-src/emacsclient -h
43 You'll hopefully have two fully working frames on separate terminals.
44 If you exit emacs, both terminals should be restored to their previous
45 states. You can close the newly opened frame and return to the shell
46 without exiting Emacs with C-x 5 0, i.e., delete-frame.
50 X, Mac, Windows and DOS support is broken, probably doesn't even
51 compile -- this will be solved later.
53 Tested under GNU/Linux only.
60 ** Support for multiple terminal devices has been added. You can
61 specify a terminal device (`tty' parameter) and a terminal type
62 (`tty-type' parameter) to `make-terminal-frame'. `tty' must be a
63 terminal device created by the updated emacsclient, or there will
64 be problems with terminal input and window resizes. (The kernel
65 notifies processes about pending input or terminal resizes only on
66 the controlling terminal, so we need emacsclient to sit on the real
67 terminal device, create SIGIO signals upon terminal input, and
68 forward SIGWINCH signals to us.)
70 You can test for the presence of multiple terminal support by
71 testing for the `multi-tty' feature.
73 ** A make-frame-on-tty function has been added to make it easier to
74 create frames on new terminals.
76 ** Emacsclient has been extended to support opening a new terminal
88 (ex-TODO items with explanations.)
90 -- Introduce a new abstraction for terminal devices.
92 (Done, see struct tty_output. The abstraction is not yet
95 -- Change the bootstrap procedure to initialize tty_list.
97 (Done, but needs review.)
99 -- Change make-terminal-frame to support specifying another tty.
101 (Done, new frame parameters: `tty' and `tty-type'.)
103 -- Implement support for reading from multiple terminals.
105 (Done, read_avail_input tries to read from each terminal, until one
106 succeeds. MULTIKBOARD is not used. Secondary terminals don't send
109 -- other-frame should cycle through the frames on the `current'
112 (Done, by trivially modifiying next_frame and prev_frame.)
114 -- Support different terminal sizes.
118 -- Make sure terminal resizes are handled gracefully. (Could be
121 (Done. We don't get automatic SIGWINCH for additional ttys,
124 -- Extend emacsclient to automatically open a new tty when it connects
127 (Done. It's an ugly hack, needs more work.)
129 -- Redisplay must refresh the topmost frame on *all* terminals, not
130 just the initial terminal.
132 (Done, but introduced an ugly redisplay problems. Ugh.)
134 -- Fix redisplay problems.
136 (Done; it turned out that the entire Wcm structure must be moved
137 inside tty_output. Why didn't I catch this earlier?)
139 -- Provide a way for emacsclient to tell Emacs that the tty has been
142 (Done, simply forward the SIGWINCH signal.)
144 -- Each keypress should automatically select the frame corresponding
145 to the terminal that it was coming from. This means that Emacs
146 must know from which terminal the last keyboard event came from.
148 (Done, it was quite simple, the input event system already
149 supported multiple frames.)
151 -- Fix SIGIO issue with secondary terminals.
153 (Done, emacsclient signals Emacs after writing to the proxy pseudo
154 terminal. Note that this means that multi-tty does not work with
157 -- Make make-terminal-frame look up the `tty' and `tty-type' frame
158 parameters from the currently selected terminal before the global
163 -- Put all cached terminal escape sequences into struct tty_output.
164 Currently, they are still stored in global variables, so we don't
165 really support multiple terminal types.
167 (Done. It was not fun.)
169 -- Implement sane error handling after initialization. (Currently
170 emacs exits if you specify a bad terminal type.) The helpful error
171 messages must still be provided when Emacs starts.
175 -- Implement terminal deletion, i.e., deleting local frames, closing
176 the tty device and restoring its previous state without exiting
179 (Done, but at the moment only called when an error happens during
180 initialization. There is a memory corruption error around this
183 -- Implement automatic deletion of terminals when the last frame on
184 that terminal is closed.
192 ** Fix mysterious memory corruption error with tty deletion. To
193 trigger it, try the following shell command:
195 while true; do TERM=no-such-terminal-definition emacsclient -h; done
197 Emacs usually dumps core after a few dozen iterations. (The bug
198 seems to be related to the xfree()ing or bzero()ing of
199 tty_output.Wcm or some other tty_output part. Maybe there are
200 outside references to struct Wcm? Why were these vars collected
201 into a struct before multi-tty support?)
203 The bug does not seem to happen if the error occurs before terminal
204 initialization or if I comment out all xfree()s in delete_frame.
205 Update: yes it does, although it is much rarer. Or maybe it's
208 ** Change emacsclient/server.el to support the -h argument better,
209 i.e. automatically close the socket when the frame is closed.
211 ** Export delete_tty to the Lisp environment, for emacsclient.
213 ** Restore tty screen after closing the terminal.
215 ** 'TERM=dumb src/emacs' does not restore the terminal state.
217 ** C-g should work on secondary terminals.
219 ** Make parts of struct tty_output accessible from Lisp. The device
220 name and the type is sufficient.
222 ** Find out why does Emacs abort when it wants to close its
225 ** Implement support for starting an interactive Emacs session without
226 an initial frame. (The user would connect to it and open frames
227 later, with emacsclient.) Not necessarily a good idea.
229 ** Support raw secondary terminals. (This one is tricky, SIGIO works
230 only on the controlling terminal. The emacsclient solution works
231 nicely, so this is not that important anyway.)
233 ** What does interrupt_input do? I tried to disable it for raw
234 secondary tty support, but it does not seem to do anything useful.
236 ** Move optimalization parameters (costs) from union output_data to
237 a backend-neutral per-device structure.
239 ** Find out the best way to support suspending Emacs with multiple
242 ** Do tty output through term_hooks, like all other display backends.
246 ** Allow simultaneous X and tty frames.
248 ** Fix Mac support (I can't do this myself).
250 ** Fix W32 support (I can't do this myself).
252 ** Fix DOS support (I can't do this myself).
256 ;;; arch-tag: 8da1619e-2e79-41a8-9ac9-a0485daad17d