This file describes various problems that have been encountered
in compiling, installing and running GNU Emacs.

* Don't use the native cc on SCO OpenServer 5.  Here is what Robert
  Lipe <robertl@arnet.com> says:

Building with the native cc on SCO OpenServer 5 produces a
disfunctional binary.  This is under investigation, but is unlikely to
be resolved before 19.13 ships.  icc [ supplied with the OpenServer 5
Development System ] generates a working binary, but you must override
the defaults while compiling font-lock.o and extents.o.  

The way I handle the build procedure is:

configure ../*14/configure --with-gcc=no --compiler="icc"
make -k    
[ procure pizza, beer ] 
cd src
make CC="icc -W0,-mP1COPT_max_tree_size=3000" font-lock.o extents.o
make LD=icc


* Don't use -O2 with gcc under Linux without also using
  -fno-strength-reduce.  gcc will generate incorrect code otherwise.
  This bug is present in at least 2.6.x and 2.7.x.

* Under some versions of OSF XEmacs runs fine if built without
optimization but will crash randomly if built with optimization.
Using 'cc -g' is not sufficient to eliminate all optimization.  Try
'cc -g -O0' instead.

* On HP/UX configure selects gcc even though it isn't actually present.

Some versions of SoftBench have an executable called 'gcc' that is not
actually the GNU C compiler.  Use the --with-gcc=no flag when running
configure.

* Solaris 2.3 /bin/sh coredumps during configuration.

This only occurs if you have LANG != C.  This is a known bug with
/bin/sh fixed by installing Patch-ID# 101613-01.

* `Pid xxx killed due to text modification or page I/O error'

On HP/UX, you can get that error when the Emacs executable is on an NFS
file system.  HP/UX responds this way if it tries to swap in a page and
does not get a response from the server within a timeout whose default
value is just ten seconds.

If this happens to you, extend the timeout period.

* `expand-file-name' fails to work on any but the machine you dumped Emacs on.

On Ultrix, if you use any of the functions which look up information
in the passwd database before dumping Emacs (say, by using
expand-file-name in site-init.el), then those functions will not work
in the dumped Emacs on any host but the one Emacs was dumped on.

The solution?  Don't use expand-file-name in site-init.el, or in
anything it loads.  Yuck - some solution.

I'm not sure why this happens; if you can find out exactly what is
going on, and perhaps find a fix or a workaround, please let us know.
Perhaps the YP functions cache some information, the cache is included
in the dumped Emacs, and is then inaccurate on any other host.

* Emacs fails to understand most Internet host names, even though
the names work properly with other programs on the same system.

This typically happens on Suns and other systems that use shared
libraries.  The cause is that the site has installed a version of the
shared library which uses a name server--but has not installed a
similiar version of the unshared library which Emacs uses.

The result is that most programs, using the shared library, work with
the nameserver, but Emacs does not.

The fix is to install an unshared library that corresponds to what you
installed in the shared library, and then relink Emacs.

* On a Sun running SunOS 4.1.1, you get this error message from GNU ld:

    /lib/libc.a(_Q_sub.o): Undefined symbol __Q_get_rp_rd referenced from text segment 

The problem is in the Sun shared C library, not in GNU ld.

The solution is to install Patch-ID# 100267-03 from Sun.

* SunOS 4.1.2: undefined symbol _get_wmShellWidgetClass

  Apparently the version of libXmu.so.a that Sun ships is hosed: it's missing
  some stuff that is in libXmu.a (the static version).  Sun has a patch for 
  this, but a workaround is to use the static version of libXmu, by changing
  the link command from "-lXmu" to "-Bstatic -lXmu -Bdynamic".  If you have
  OpenWindows 3.0, ask Sun for these patches:
    100512-02       4.1.x OpenWindows 3.0 libXt Jumbo patch
    100573-03       4.1.x OpenWindows 3.0 undefined symbols with shared libXmu

* Random other SunOS 4.1.[12] link errors.

  The X headers and libraries that Sun ships in /usr/{include,lib}/X11 are
  broken.  Use the ones in /usr/openwin/{include,lib} instead.

* Bus errors on startup when compiled with Sun's "acc" (in the routine
  make_string_internal() called from initialize_environment_alist())

  The Sun ANSI compiler doesn't place uninitialized static variables in BSS
  space like other compilers do.  This breaks emacs.  If you want to use acc,
  you need to make the file "lastfile.o" be the *first* file in the link 
  command.  Better yet, use Lucid C or GCC.

* The compiler generates lots and lots of syntax errors.

Are you using an ANSI C compiler, like lcc or gcc?  The SunOS 4.1 bundled cc
is not ANSI.

If X has not been configured to compile itself using lcc, gcc, or another ANSI
compiler, then you will have to hack the automatically-generated makefile in
the `lwlib' directory by hand to make it use an ANSI compiler.

* When using gcc, you get the error message "undefined symbol __fixunsdfsi".
* When using gcc, you get the error message "undefined symbol __main".

This means that you need to link with the gcc library.  It may be called
"gcc-gnulib" or "libgcc.a"; figure out where it is, and define LIB_GCC in
config.h to point to it.

It may also work to use the GCC version of `ld' instead of the standard one.

* When compiling with X11, you get "undefined symbol _XtStrings".

This means that you are trying to link emacs against the X11r4 version of
libXt.a, but you have compiled either Emacs or the code in the lwlib
subdirectory with the X11r5 header files.  That doesn't work.

Remember, you can't compile lwlib for r4 and emacs for r5, or vice versa.
They must be in sync.

* Self documentation messages are garbled.

This means that the file `etc/DOC-...' doesn't properly correspond
with the Emacs executable.  Redumping Emacs and then installing the
corresponding pair of files should fix the problem.

* M-x shell immediately responds "Process shell exited abnormally with code 1".

This is often due to inability to run the program `env'.
This should be in the `etc' subdirectory of the directory
where Emacs is installed, and it should be marked executable.

* Trouble using ptys on AIX.

People often instll the pty devices on AIX incorrectly.
Use `smit pty' to reinstall them properly.

* Shell mode on HP/UX gives the message, "`tty`: Ambiguous".

christos@theory.tn.cornell.edu says:

The problem is that in your .cshrc you have something that tries to
execute `tty`. If you are not running the shell on a real tty then 
tty will print "not a tty". Csh expects one word in some places, 
but tty is giving it back 3.

The solution is to add a pair of quotes around `tty` to make it a single
word: 

if (`tty` == "/dev/console") 

should be changed to:

if ("`tty`" == "/dev/console") 

Even better, move things that set up terminal sections out of .cshrc
and into .login.

* With process-connection-type set to t, each line of subprocess output is
  terminated with a ^M, making ange-ftp and GNUS not work.

On SunOS systems, this problem has been seen to be a result of an incomplete
installation of gcc 2.2 which allowed some non-ANSI compatible include files
into the compilation.  In particular this affected virtually all ioctl() calls.

* Once you pull down a menu from the menubar, it won't go away.

It has been claimed that this is caused by a bug in certain very old (1990?)
versions of the twm window manager.  It doesn't happen with recent vintages,
or with other window managers.

* Emacs ignores the "help" key when running OLWM.

OLWM grabs the help key, and retransmits it to the appropriate client using
XSendEvent.  Allowing emacs to react to synthetic events is a security hole,
so this is turned off by default.  You can enable it by setting the variable
x-allow-sendevents to t.  You can also cause fix this by telling OLWM to not
grab the help key, with the null binding "OpenWindows.KeyboardCommand.Help:".

* Something awful happens when I type M-ESC, instead of `eval-expression'.

MWM intercepts this and several other keys.  Turn this off by adding this to
your resources: "mwm*keyBindings: NoKeyBindings".

* Emacs starts in a directory other than the one that is current in the shell.

If the PWD environment variable exists, Emacs uses this variable as
the initial working directory.

Some shells automatically update this variable, while other shells fail
to do so.  If you use two such shells in combination, the variable can
end up wrong.  This confuses Emacs.

The solution is to put something in the start-up file for the shell
that does not update PWD, to get rid of that environment variable.
For example, in csh, use `unsetenv PWD'.

* Emacs gets error message from linker on Sun.

If the error message says that a symbol such as `f68881_used' or
`ffpa_used' or `start_float' is undefined, this probably indicates
that you have compiled some libraries, such as the X libraries, 
with a floating point option other than the default.

It's not terribly hard to make this work with small changes in
crt0.c together with linking with Fcrt1.o, Wcrt1.o or Mcrt1.o.
However, the easiest approach is to build Xlib with the default
floating point option: -fsoft to decide at run time what hardware 
is available.

* Keyboard input gets confused after a beep when using a DECserver
  as a concentrator.

This problem seems to be a matter of configuring the DECserver to use
7 bit characters rather than 8 bit characters.

* M-x shell persistently reports "Process shell exited abnormally with code 1".

This happened on Suns as a result of what is said to be a bug in Sunos
version 4.0.x.  The only fix was to reboot the machine. 

* Programs running under terminal emulator do not recognize `emacs'
  terminal type.

The cause of this is a shell startup file that sets the TERMCAP
environment variable.  The terminal emulator uses that variable to
provide the information on the special terminal type that Emacs
emulates.

Rewrite your shell startup file so that it does not change TERMCAP
in such a case.  You could use the following conditional which sets
it only if it is undefined.

    if ( ! ${?TERMCAP} ) setenv TERMCAP ~/my-termcap-file

Or you could set TERMCAP only when you set TERM--which should not
happen in a non-login shell.

* Error compiling sysdep.c, "sioctl.h: no such file or directory".

Among USG systems with TIOCGWINSZ, some require sysdep.c to include
the file sioctl.h; on others, sioctl.h does not exist.  We don't know
how to distinguish these two kind of systems, so currently we try to
include sioctl.h on all of them.  If this #include gets an error, just
delete it.

* Problem with remote X server on Suns.

On a Sun, running Emacs on one machine with the X server on another
may not work if you have used the unshared system libraries.  This
is because the unshared libraries fail to use YP for host name lookup.
As a result, the host name you specify may not be recognized.

* Watch out for .emacs files and EMACSLOADPATH environment vars

These control the actions of Emacs.
~/.emacs is your Emacs init file.
EMACSLOADPATH overrides which directories the function
"load" will search.

If you observe strange problems, check for these and get rid
of them, then try again.

* Shell mode ignores interrupts on Apollo Domain

You may find that M-x shell prints the following message:

   Warning: no access to tty; thus no job control in this shell...

This can happen if there are not enough ptys on your system.
Here is how to make more of them.

    % cd /dev
    % ls pty*
    # shows how many pty's you have. I had 8, named pty0 to pty7)
    % /etc/crpty 8
    # creates eight new pty's

* Fatal signal in the command  temacs -l loadup inc dump

This command is the final stage of building Emacs.  It is run by the
Makefile in the src subdirectory, or by build.com on VMS.

It has been known to get fatal errors due to insufficient swapping
space available on the machine.

On 68000's, it has also happened because of bugs in the
subroutine `alloca'.  Verify that `alloca' works right, even
for large blocks (many pages).

* test-distrib says that the distribution has been clobbered
* or, temacs prints "Command key out of range 0-127"
* or, temacs runs and dumps xemacs, but xemacs totally fails to work.
* or, temacs gets errors dumping xemacs

This can be because the .elc files have been garbled.  Do not be
fooled by the fact that most of a .elc file is text: these are
binary files and can contain all 256 byte values.

In particular `shar' cannot be used for transmitting GNU Emacs.
It typically truncates "lines".  What appear to be "lines" in
a binary file can of course be of any length.  Even once `shar'
itself is made to work correctly, `sh' discards null characters
when unpacking the shell archive.

I have also seen character \177 changed into \377.  I do not know
what transfer means caused this problem.  Various network
file transfer programs are suspected of clobbering the high bit.

If you have a copy of Emacs that has been damaged in its
nonprinting characters, you can fix them:

 1) Record the names of all the .elc files.
 2) Delete all the .elc files.
 3) Recompile alloc.c with a value of PURESIZE twice as large.
     You might as well save the old alloc.o.
 4) Remake xemacs.  It should work now.
 5) Running xemacs, do Meta-x byte-compile-file repeatedly
  to recreate all the .elc files that used to exist.
  You may need to increase the value of the variable
  max-lisp-eval-depth to succeed in running the compiler interpreted
  on certain .el files.  400 was sufficient as of last report.
 6) Reinstall the old alloc.o (undoing changes to alloc.c if any)
  and remake temacs.
 7) Remake xemacs.  It should work now, with valid .elc files.

* temacs prints "Pure Lisp storage exhausted"

This means that the Lisp code loaded from the .elc and .el
files during  temacs -l loadup inc dump  took up more
space than was allocated.

This could be caused by
 1) adding code to the preloaded Lisp files
 2) adding more preloaded files in loadup.el
 3) having a site-init.el or site-load.el which loads files.
   Note that ANY site-init.el or site-load.el is nonstandard;
   if you have received Emacs from some other site
   and it contains a site-init.el or site-load.el file, consider
   deleting that file.
 4) getting the wrong .el or .elc files
   (not from the directory you expected).
 5) deleting some .elc files that are supposed to exist.
   This would cause the source files (.el files) to be
   loaded instead.  They take up more room, so you lose.
 6) a bug in the Emacs distribution which underestimates
   the space required.

If the need for more space is legitimate, change the definition
of PURESIZE in puresize.h.

But in some of the cases listed above, this problem is a consequence
of something else that is wrong.  Be sure to check and fix the real
problem.

* Changes made to .el files do not take effect.

You may have forgotten to recompile them into .elc files.
Then the old .elc files will be loaded, and your changes
will not be seen.  To fix this, do M-x byte-recompile-directory
and specify the directory that contains the Lisp files.

* Things which should be bold or italic (such as the initial copyright notice)
  are not.

The fonts of the "bold" and "italic" faces are generated from the font of
the "default" face; in this way, your bold and italic fonts will have the
appropriate size and family.  However, emacs can only be clever in this
way if you have specified the default font using the XLFD (X Logical Font
Description) format, which looks like

	*-courier-medium-r-*-*-*-120-*-*-*-*-*-*

if you use any of the other, less strict font name formats, some of which
look like
		lucidasanstypewriter-12
and		fixed
and		9x13

then emacs won't be able to guess the names of the "bold" and "italic"
versions.  All X fonts can be referred to via XLFD-style names, so you
should use those forms.  See the man pages for X(1), xlsfonts(1), and
xfontsel(1).

* The dumped Emacs (xemacs) crashes when run, trying to write pure data.

Two causes have been seen for such problems.

1) On a system where getpagesize is not a system call, it is defined
as a macro.  If the definition (in both unexec.c and malloc.c) is wrong,
it can cause problems like this.  You might be able to find the correct
value in the man page for a.out (5).

2) Some systems allocate variables declared static among the
initialized variables.  Emacs makes all initialized variables in most
of its files pure after dumping, but the variables declared static and
not initialized are not supposed to be pure.  On these systems you
may need to add "#define static" to the m- or the s- file.

* Reading and writing files is very very slow.

Try evaluating the form (setq lock-directory nil) and see if that helps.
There is a problem with file-locking on some systems (possibly related
to NFS) that I don't understand.  Please send mail to the address 
xemacs@cs.uiuc.edu if you figure this one out.

* Compilation errors on VMS.

You will get warnings when compiling on VMS because there are
variable names longer than 32 (or whatever it is) characters.
This is not an error.  Ignore it.

VAX C does not support #if defined(foo).  Uses of this construct
were removed, but some may have crept back in.  They must be rewritten.

There is a bug in the C compiler which fails to sign extend characters
in conditional expressions.  The bug is:
	char c = -1, d = 1;
	int i;

	i = d ? c : d;
The result is i == 255;  the fix is to typecast the char in the
conditional expression as an (int).  Known occurrences of such
constructs in Emacs have been fixed.

* "Symbol's value as variable is void: unread-command-char".
* "Wrong type argument: arrayp, #<keymap 143 entries>"
* "Wrong type argument: stringp, [#<keypress-event return>]"

There are a few incompatible changes in XEmacs, and these are the
symptoms.  Some of the emacs-lisp code you are running needs to be
updated to be compatible with XEmacs.

We have provided modified versions of several popular emacs packages (GNUS, 
VM, etc) which are compatible with this version of emacs.  Check to make
sure you have not set your load-path so that your private copies of these
packages are being found before the versions in the lisp directory.

Make sure that your load-path and your $EMACSLOADPATH environment variable
are not pointing at an Emacs18 lisp directory.  This will cripple emacs.

* rmail gets error getting new mail

rmail gets new mail from /usr/spool/mail/$USER using a program
called `movemail'.  This program interlocks with /bin/mail using
the protocol defined by /bin/mail.

There are two different protocols in general use.  One of them uses
the `flock' system call.  The other involves creating a lock file;
`movemail' must be able to write in /usr/spool/mail in order to do
this.  You control which one is used by defining, or not defining,
the macro MAIL_USE_FLOCK in config.h or the m- or s- file it includes.
IF YOU DON'T USE THE FORM OF INTERLOCKING THAT IS NORMAL ON YOUR
SYSTEM, YOU CAN LOSE MAIL!

If your system uses the lock file protocol, and fascist restrictions
prevent ordinary users from writing the lock files in /usr/spool/mail,
you may need to make `movemail' setgid to a suitable group such as
`mail'.  You can use these commands (as root):

	chgrp mail movemail
	chmod 2755 movemail

* Emacs won't work with X-windows if the value of DISPLAY is HOSTNAME:0.
* GNUs can't make contact with the specified host for nntp.

Some people have found that Emacs was unable to connect to the local
host by name, as in DISPLAY=prep:0 if you are running on prep, but
could handle DISPLAY=unix:0.  Here is what tale@rpi.edu said:

    Seems as though gethostbyname was bombing somewhere along the way.
    Well, we had just upgrade from SunOS 3.5 (which X11 was built under) to
    SunOS 4.0.1.  Any new X applications which tried to be built with the
    pre OS-upgrade libraries had the same problems which Emacs was having.
    Missing /etc/resolv.conf for a little while (when one of the libraries
    was built?) also might have had a hand in it.

    The result of all of this (with some speculation) was that we rebuilt
    X and then rebuilt Emacs with the new libraries.  Works as it should
    now.  Hoorah.

If you have already installed the name resolver in the file libresolv.a,
then you need to compile Emacs to use that library.  The easiest way to
do this is to add to config.h a definition of LIBS_SYSTEM, LIBS_MACHINE
or LIB_STANDARD which uses -lresolv.  Watch out!  If you redefine a macro
that is already in use in your configuration to supply some other libraries,
be careful not to lose the others.

Thus, you could start by adding this to config.h:

#define LIBS_SYSTEM -lresolv

Then if this gives you an error for redefining a macro, and you see that
the s- file defines LIBS_SYSTEM as -lfoo -lbar, you could change config.h
again to say this:

#define LIBS_SYSTEM -lresolv -lfoo -lbar

The reason this is sometimes a problem for Emacs and not for other programs
is that Emacs must be statically linked, while most other programs are
dynamically linked.  Sometimes people install patches or updates into the
dynamic version of a library without installing them into the static version
as well, leading to these inconsistencies.

In particular, people often change the definition of `gethostbyname' in
the dynamic version of libc.a to use a different method of host resolution,
but forget to do the same to the static version of that library.

* Emacs spontaneously displays "I-search: " at the bottom of the screen.

This means that Control-S/Control-Q "flow control" is being used.
C-s/C-q flow control is bad for Emacs editors because it takes away
C-s and C-q as user commands.  Since editors do not output long streams
of text without user commands, there is no need for a user-issuable
"stop output" command in an editor; therefore, a properly designed
flow control mechanism would transmit all possible input characters
without interference.  Designing such a mechanism is easy, for a person
with at least half a brain.

There are three possible reasons why flow control could be taking place:

  1) Terminal has not been told to disable flow control
  2) Insufficient padding for the terminal in use
  3) Some sort of terminal concentrator or line switch is responsible

First of all, many terminals have a set-up mode which controls
whether they generate flow control characters.  This must be
set to "no flow control" in order for Emacs to work.  Sometimes
there is an escape sequence that the computer can send to turn
flow control off and on.  If so, perhaps the termcap `ti' string
should turn flow control off, and the `te' string should turn it on.

Once the terminal has been told "no flow control", you may find it
needs more padding.  The amount of padding Emacs sends is controlled
by the termcap entry for the terminal in use, and by the output baud
rate as known by the kernel.  The shell command `stty' will print
your output baud rate; `stty' with suitable arguments will set it if
it is wrong.  Setting to a higher speed causes increased padding.  If
the results are wrong for the correct speed, there is probably a
problem in the termcap entry.  You must speak to a local Unix wizard
to fix this.  Perhaps you are just using the wrong terminal type.

For terminals that lack a "no flow control" mode, sometimes just
giving lots of padding will prevent actual generation of flow control
codes.  You might as well try it.

If you are really unlucky, your terminal is connected to the computer
through a concentrator which sends flow control to the computer, or it
insists on sending flow control itself no matter how much padding you
give it.  You are screwed!  You should replace the terminal or
concentrator with a properly designed one.  In the mean time,
some drastic measures can make Emacs semi-work.

One drastic measure to ignore C-s and C-q, while sending enough
padding that the terminal will not really lose any output.
Ignoring C-s and C-q can be done by using keyboard-translate-table
to map them into an undefined character such as C-^ or C-\.  Sending
lots of padding is done by changing the termcap entry.  Here is how
to make such a keyboard-translate-table:

    (let ((the-table (make-string 128 0)))
      ;; Default is to translate each character into itself.
      (let ((i 0))
	(while (< i 128)
	  (aset the-table i i)
	  (setq i (1+ i))))
      ;; Swap C-s with C-\
      (aset the-table ?\C-\\ ?\C-s)
      (aset the-table ?\C-s ?\C-\\)
      ;; Swap C-q with C-^
      (aset the-table ?\C-^ ?\C-q)
      (aset the-table ?\C-q ?\C-^)
      (setq keyboard-translate-table the-table))

An even more drastic measure is to make Emacs use flow control.
To do this, evaluate the Lisp expression (set-input-mode nil t).
Emacs will then interpret C-s and C-q as flow control commands.  (More
precisely, it will allow the kernel to do so as it usually does.)  You
will lose the ability to use them for Emacs commands.  Also, as a
consequence of using CBREAK mode, the terminal's Meta-key, if any,
will not work, and C-g will be liable to cause a loss of output which
will produce garbage on the screen.  (These problems apply to 4.2BSD;
they may not happen in 4.3 or VMS, and I don't know what would happen
in sysV.)  You can use keyboard-translate-table, as shown above,
to map two other input characters (such as C-^ and C-\) into C-s and
C-q, so that you can still search and quote.

I have no intention of ever redisigning the Emacs command set for
the assumption that terminals use C-s/C-q flow control.  This
flow control technique is a bad design, and terminals that need
it are bad merchandise and should not be purchased.  If you can
get some use out of GNU Emacs on inferior terminals, I am glad,
but I will not make Emacs worse for properly designed systems
for the sake of inferior systems.

* Control-S and Control-Q commands are ignored completely.

For some reason, your system is using brain-damaged C-s/C-q flow
control despite Emacs's attempts to turn it off.  Perhaps your
terminal is connected to the computer through a concentrator
that wants to use flow control.

You should first try to tell the concentrator not to use flow control.
If you succeed in this, try making the terminal work without
flow control, as described in the preceding section.

If that line of approach is not successful, map some other characters
into C-s and C-q using keyboard-translate-table.  The example above
shows how to do this with C-^ and C-\.

* Control-S and Control-Q commands are ignored completely on a net connection.

Some versions of rlogin (and possibly telnet) do not pass flow
control characters to the remote system to which they connect.
On such systems, emacs on the remote system cannot disable flow
control on the local system.

One way to cure this is to disable flow control on the local host
(the one running rlogin, not the one running rlogind) using the
stty command, before starting the rlogin process.  On many systems,
"stty start u stop u" will do this.

Some versions of tcsh will prevent even this from working.  One way
around this is to start another shell before starting rlogin, and
issue the stty command to disable flow control from that shell.

* Screen is updated wrong, but only on one kind of terminal.

This could mean that the termcap entry you are using for that
terminal is wrong, or it could mean that Emacs has a bug handing
the combination of features specified for that terminal.

The first step in tracking this down is to record what characters
Emacs is sending to the terminal.  Execute the Lisp expression
(open-termscript "./emacs-script") to make Emacs write all
terminal output into the file ~/emacs-script as well; then do
what makes the screen update wrong, and look at the file
and decode the characters using the manual for the terminal.
There are several possibilities:

1) The characters sent are correct, according to the terminal manual.

In this case, there is no obvious bug in Emacs, and most likely you
need more padding, or possibly the terminal manual is wrong.

2) The characters sent are incorrect, due to an obscure aspect
 of the terminal behavior not described in an obvious way
 by termcap.

This case is hard.  It will be necessary to think of a way for
Emacs to distinguish between terminals with this kind of behavior
and other terminals that behave subtly differently but are
classified the same by termcap; or else find an algorithm for
Emacs to use that avoids the difference.  Such changes must be
tested on many kinds of terminals.

3) The termcap entry is wrong.

See the file etc/TERMS for information on changes
that are known to be needed in commonly used termcap entries
for certain terminals.

4) The characters sent are incorrect, and clearly cannot be
 right for any terminal with the termcap entry you were using.

This is unambiguously an Emacs bug, and can probably be fixed
in termcap.c, tparam.c, term.c, scroll.c, cm.c or dispnew.c.

* Output from Control-V is slow.

On many bit-map terminals, scrolling operations are fairly slow.
Often the termcap entry for the type of terminal in use fails
to inform Emacs of this.  The two lines at the bottom of the screen
before a Control-V command are supposed to appear at the top after
the Control-V command.  If Emacs thinks scrolling the lines is fast,
it will scroll them to the top of the screen.

If scrolling is slow but Emacs thinks it is fast, the usual reason is
that the termcap entry for the terminal you are using does not
specify any padding time for the `al' and `dl' strings.  Emacs
concludes that these operations take only as much time as it takes to
send the commands at whatever line speed you are using.  You must
fix the termcap entry to specify, for the `al' and `dl', as much
time as the operations really take.

Currently Emacs thinks in terms of serial lines which send characters
at a fixed rate, so that any operation which takes time for the
terminal to execute must also be padded.  With bit-map terminals
operated across networks, often the network provides some sort of
flow control so that padding is never needed no matter how slow
an operation is.  You must still specify a padding time if you want
Emacs to realize that the operation takes a long time.  This will
cause padding characters to be sent unnecessarily, but they do
not really cost much.  They will be transmitted while the scrolling
is happening and then discarded quickly by the terminal.

Most bit-map terminals provide commands for inserting or deleting
multiple lines at once.  Define the `AL' and `DL' strings in the
termcap entry to say how to do these things, and you will have
fast output without wasted padding characters.  These strings should
each contain a single %-spec saying how to send the number of lines
to be scrolled.  These %-specs are like those in the termcap
`cm' string.

You should also define the `IC' and `DC' strings if your terminal
has a command to insert or delete multiple characters.  These
take the number of positions to insert or delete as an argument.

A `cs' string to set the scrolling region will reduce the amount
of motion you see on the screen when part of the screen is scrolled.

* Your Delete key sends a Backspace to the terminal, using an AIXterm.

The solution is to include in your .Xdefaults the lines:

   *aixterm.Translations: #override <Key>BackSpace: string(0x7f)
   aixterm*ttyModes: erase ^?

This makes your Backspace key send DEL (ASCII 127).

* You type Control-H (Backspace) expecting to delete characters.

Put `stty dec' in your .login file and your problems will disappear
after a day or two.

The choice of Backspace for erasure was based on confusion, caused by
the fact that backspacing causes erasure (later, when you type another
character) on most display terminals.  But it is a mistake.  Deletion
of text is not the same thing as backspacing followed by failure to
overprint.  I do not wish to propagate this confusion by conforming
to it.

For this reason, I believe `stty dec' is the right mode to use,
and I have designed Emacs to go with that.  If there were a thousand
other control characters, I would define Control-h to delete as well;
but there are not very many other control characters, and I think
that providing the most mnemonic possible Help character is more
important than adapting to people who don't use `stty dec'.

If you are obstinate about confusing buggy overprinting with deletion,
you can redefine Backspace in your .emacs file:
  (global-set-key "\b" 'delete-backward-char)
You may then wish to put the function  help-command  on some
other key.  I leave to you the task of deciding which key.

* Editing files through RFS gives spurious "file has changed" warnings.
It is possible that a change in Emacs 18.37 gets around this problem,
but in case not, here is a description of how to fix the RFS bug that
causes it.

    There was a serious pair of bugs in the handling of the fsync() system
    call in the RFS server.

    The first is that the fsync() call is handled as another name for the
    close() system call (!!).  It appears that fsync() is not used by very
    many programs; Emacs version 18 does an fsync() before closing files
    to make sure that the bits are on the disk.

    This is fixed by the enclosed patch to the RFS server.

    The second, more serious problem, is that fsync() is treated as a
    non-blocking system call (i.e., it's implemented as a message that
    gets sent to the remote system without waiting for a reply).  Fsync is
    a useful tool for building atomic file transactions.  Implementing it
    as a non-blocking RPC call (when the local call blocks until the sync
    is done) is a bad idea; unfortunately, changing it will break the RFS
    protocol.  No fix was supplied for this problem.

    (as always, your line numbers may vary)

    % rcsdiff -c -r1.2 serversyscall.c
    RCS file: RCS/serversyscall.c,v
    retrieving revision 1.2
    diff -c -r1.2 serversyscall.c
    *** /tmp/,RCSt1003677   Wed Jan 28 15:15:02 1987
    --- serversyscall.c     Wed Jan 28 15:14:48 1987
    ***************
    *** 163,169 ****
	    /*
	     * No return sent for close or fsync!
	     */
    !       if (syscall == RSYS_close || syscall == RSYS_fsync)
		    proc->p_returnval = deallocate_fd(proc, msg->m_args[0]);
	    else
	    {
    --- 166,172 ----
	    /*
	     * No return sent for close or fsync!
	     */
    !       if (syscall == RSYS_close)
		    proc->p_returnval = deallocate_fd(proc, msg->m_args[0]);
	    else
	    {

* Vax C compiler bugs affecting Emacs.

You may get one of these problems compiling Emacs:

   foo.c line nnn: compiler error: no table entry for op STASG
   foo.c: fatal error in /lib/ccom

These are due to bugs in the C compiler; the code is valid C.
Unfortunately, the bugs are unpredictable: the same construct
may compile properly or trigger one of these bugs, depending
on what else is in the source file being compiled.  Even changes
in header files that should not affect the file being compiled
can affect whether the bug happens.  In addition, sometimes files
that compile correctly on one machine get this bug on another machine.

As a result, it is hard for me to make sure this bug will not affect
you.  I have attempted to find and alter these constructs, but more
can always appear.  However, I can tell you how to deal with it if it
should happen.  The bug comes from having an indexed reference to an
array of Lisp_Objects, as an argument in a function call:
  Lisp_Object *args;
  ...
   ... foo (5, args[i], ...)...
putting the argument into a temporary variable first, as in
  Lisp_Object *args;
  Lisp_Object tem;
  ...
   tem = args[i];
   ... foo (r, tem, ...)...
causes the problem to go away.
The `contents' field of a Lisp vector is an array of Lisp_Objects,
so you may see the problem happening with indexed references to that.

* 68000 C compiler problems

Various 68000 compilers have different problems.
These are some that have been observed.

** Using value of assignment expression on union type loses.
This means that  x = y = z;  or  foo (x = z);  does not work
if x is of type Lisp_Object.

** "cannot reclaim" error.

This means that an expression is too complicated.  You get the correct
line number in the error message.  The code must be rewritten with
simpler expressions.

** XCONS, XSTRING, etc macros produce incorrect code.

If temacs fails to run at all, this may be the cause.
Compile this test program and look at the assembler code:

struct foo { char x; unsigned int y : 24; };

lose (arg)
     struct foo arg;
{
  test ((int *) arg.y);
}

If the code is incorrect, your compiler has this problem.
In the XCONS, etc., macros in lisp.h you must replace (a).u.val with
((a).u.val + coercedummy) where coercedummy is declared as int.

This problem will not happen if the m-...h file for your type
of machine defines NO_UNION_TYPE.  That is the recommended setting now.

* C compilers lose on returning unions

I hear that some C compilers cannot handle returning a union type.
Most of the functions in GNU Emacs return type Lisp_Object, which is
defined as a union on some rare architectures.

This problem will not happen if the m-...h file for your type
of machine defines NO_UNION_TYPE.  That is the recommended setting now.

* When Emacs tries to ring the bell, you get an error like

	audio: sst_open: SETQSIZE" Invalid argument
	audio: sst_close: SETREG MMR2, Invalid argument

you have probably compiled using an ANSI C compiler, but with non-ANSI include
files.  In particular, on Suns, the file /usr/include/sun/audioio.h uses the
_IOW macro to define the constant AUDIOSETQSIZE.  _IOW in turn uses a K&R
preprocessor feature that is now explicitly forbidden in ANSI preprocessors,
namely substitution inside character constants.  All ANSI C compilers must 
provide a workaround for this problem.  Lucid's C compiler is shipped with a 
new set of system include files.  If you are using GCC, there is a script
called fixincludes that creates new versions of some system include files that
use this obsolete feature.

* The `Alt' key doesn't behave as `Meta' when running DECwindows.

The default DEC keyboard mapping has the Alt keys set up to generate the
keysym `Multi_key', which has a meaning to xemacs which is distinct from that
of the `Meta_L' and `Meta-R' keysyms.  A second problem is that certain keys
have the Mod2 modifier attached to them for no adequately explored reason.
The correct fix is to pass this file to xmodmap upon starting X:

	clear mod2
	keysym Multi_key = Alt_L
	add mod1 = Alt_L
	add mod1 = Alt_R

* I get complaints about the mapping of my HP keyboard at startup, but I
  haven't changed anything.

The default HP keymap is set up to have Mod1 assigned to two different keys:
Meta_L and Mode_switch (even though there is not actually a Mode_switch key on
the keyboard -- it uses an "imaginary" keycode.)  There actually is a reason
for this, but it's not a good one.  The correct fix is to execute this command
upon starting X:

	xmodmap -e 'remove mod1 = Mode_switch'

* I have focus problems when I use `M-o' to switch to another screen without
  using the mouse.

The focus issues with a program like XEmacs, which has multiple homogeneous
top-level windows, are very complicated, and as a result, most window managers
don't implement them correctly.

The R4/R5 version of twm (and all of its descendants) had buggy focus
handling; there is a patch in .../xemacs/etc/twm-patch which fixes this.
Sufficiently recent versions of tvtwm do not need this patch, but most other
versions of twm do.  If you need to apply this patch, please try to get it
integrated by the maintainer of whichever version of twm you're using.

In addition, if you're using twm, make sure you have not specified
"NoTitleFocus" in your .tvtwmrc file.  The very nature of this option makes
twm do some illegal focus tricks, even with the patch.

It is known that olwm and olvwm are buggy, and in different ways.  If you're 
using click-to-type mode, try using point-to-type, or vice versa.

In older versions of NCDwm, one could not even type at XEmacs windows.  This
has been fixed in newer versions (2.4.3, and possibly earlier).

(Many people suggest that XEmacs should warp the mouse when focusing on
another screen in point-to-type mode.  This is not ICCCM-compliant behavior.
Implementing such policy is the responsibility of the window manager itself,
it is not legal for a client to do this.)

* My buffers are full of \000 characters or otherwise corrupt.

Some compilers have trouble with gmalloc.c and ralloc.c; try recompiling
without optimization.  If that doesn't work, try recompiling with
SYSTEM_MALLOC defined, and/or with REL_ALLOC undefined.

* Some packages that worked before now cause the error
  Wrong type argument: arrayp, #<face ... >

Code which uses the `face' accessor functions must be recompiled with xemacs
19.9 or later.  The functions whose callers must be recompiled are: face-font,
face-foreground, face-background, face-background-pixmap, and face-underline-p.
The .elc files generated by version 19.9 will work in 19.6 and 19.8, but older
.elc files which contain calls to these functions will not work in 19.9.

* On Solaris 2.* I get undefined symbols from libcurses.a.

You probably have /usr/ucblib/ on your LD_LIBRARY_PATH.  Do the link with
LD_LIBRARY_PATH unset.

* I don't have `xmkmf' and `imake' on my HP.

You can get these standard X tools by anonymous FTP to hpcvaaz.cv.hp.com.
Essentially all X programs need these.

* When emacs starts up, I get lots of warnings about unknown keysyms.

If you are running the prebuilt binaries, the Motif library expects to find
certain thing in the XKeysymDB file.  This file is normally in /usr/lib/X11/
or in /usr/openwin/lib/.  If you keep yours in a different place, set the
environment variable $XKEYSYMDB to point to it before starting emacs.  If 
you still have the problem after doing that, perhaps your version of X is 
too old.  There is a copy of the MIT X11R5 XKeysymDB file in the emacs `etc'
directory.  Try using that one.

* My X resources used to work, and now some of them are being ignored.

Check the resources in .../etc/Emacs.ad (which is the same as the file
sample.Xdefaults).  Perhaps some of the default resources built in to 
emacs are now overriding your existing resources.  Copy and edit the
resources in Emacs.ad as necessary.
