Cygwin patches (mostly documentation)

Cygwin patches (mostly documentation)

[Ken Brown]

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In http://lists.gnu.org/archive/html/emacs-devel/2009-05/msg00310.html
Eli asked me to look at Cygwin-related problems in etc/PROBLEMS to see
if any can be dealt with before the next release.

I'm attaching a set of patches for your consideration.  These are mostly 
updates to etc/PROBLEMS to reflect the current state of problems that 
have been reported, but one is to src/s/cygwin.h.  This was discussed 
earlier 
(http://lists.gnu.org/archive/html/emacs-devel/2009-05/msg00418.html) 
but, as far as I know, hasn't been applied yet.  One of the patches to 
etc/PROBLEMS presupposes that the patch to cygwin.h has been applied.

In the same thread, Lennart asked me to take a look at the cygwin 
information on EmacsWiki.  I've done that, and there's a lot of obsolete 
information.  At this point, however, I think it might be best to wait a 
few weeks before trying to correct this.  A new release of cygwin (1.7) 
is expected by the end of the month.  By the time this comes out, I 
expect to have updated cygwin's emacs distribution to some version of 
emacs-23, with updated documentation.  When that happens, I can put an 
appropriate announcement on EmacsWiki with a link to the documentation.

Ken

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--- origsrc/emacs-23.0.94/etc/PROBLEMS	2009-05-14 16:43:38.000000000 -0400
+++ src/emacs-23.0.94/etc/PROBLEMS	2009-06-01 19:11:48.073476800 -0400
@@ -254,6 +254,18 @@ Cygwin, that becomes the Cygwin supplied
 Cygwin malloc, the Cygwin memalign always returns ENOSYS.  A fix for this
 problem would be welcome.
 
+A workaround is to set G_SLICE=always-malloc before starting emacs.
+For example, in bash,
+
+  G_SLICE=always-malloc emacs
+
+or put
+
+  export G_SLICE=always-malloc
+
+in one of the bash startup files.  This  also has to be done before
+building emacs on Cygwin with Gtk+.
+
 * General runtime problems
 
 ** Lisp problems
@@ -2268,34 +2280,6 @@ and Language Options" applet needed to f
 changes the keyboard layout depends on your Windows version; for XP,
 in the Languages tab, click "Details" and then "Key Settings".)
 
-** Cygwin build of Emacs hangs after rebasing Cygwin DLLs
-
-Usually, on Cygwin, one needs to rebase the DLLs if an application
-aborts with a message like this:
-
-  C:\cygwin\bin\python.exe: *** unable to remap C:\cygwin\bin\cygssl.dll to
-  same address as parent(0xDF0000) != 0xE00000
-
-However, since Cygwin DLL 1.5.17 was released, after such rebasing,
-Emacs hangs.
-
-This was reported to happen for Emacs 21.2 and also for the pretest of
-Emacs 22.1 on Cygwin.
-
-To work around this, build Emacs like this:
-
-  LDFLAGS='-Wl,--enable-auto-import -Wl,--enable-auto-image-base' ./configure
-  make LD='$(CC)'
-  make LD='$(CC)' install
-
-This produces an Emacs binary that is independent of rebasing.
-
-Note that you _must_ use LD='$(CC)' in the last two commands above, to
-prevent GCC from passing the "--image-base 0x20000000" option to the
-linker, which is what it does by default.  That option produces an
-Emacs binary with the base address 0x20000000, which will cause Emacs
-to hang after Cygwin DLLs are rebased.
-
 ** Interrupting Cygwin port of Bash from Emacs doesn't work.
 
 Cygwin 1.x builds of the ported Bash cannot be interrupted from the
@@ -2542,17 +2526,12 @@ files are installed. Then use:
 
 (using the location of the 32-bit X libraries on your system).
 
-*** Building the Cygwin port for MS-Windows can fail with some GCC versions
+*** Building the Cygwin port of emacs requires GCC 4
 
-Building Emacs 22 with Cygwin builds of GCC 3.4.4-1 and 3.4.4-2 is
-reported to either fail or cause Emacs to segfault at run time.  In
-addition, the Cygwin GCC 3.4.4-2 has problems with generating debug
-info.  Cygwin users are advised not to use these versions of GCC for
-compiling Emacs.  GCC versions 4.0.3, 4.0.4, 4.1.1, and 4.1.2
-reportedly build a working Cygwin binary of Emacs, so we recommend
-these GCC versions.  Note that these versions of GCC, 4.0.3, 4.0.4,
-4.1.1, and 4.1.2, are currently the _only_ versions known to succeed
-in building Emacs (as of v22.1).
+As of Emacs 22.1, there have been problems with Cygwin builds of Emacs
+using GCC 3.  Cygwin users are advised to use GCC 4.  As far as we
+know, there have been no problems with Cygwin builds of Emacs using
+GCC 4.
 
 *** Building the native MS-Windows port with Cygwin GCC can fail.
 
--- origsrc/emacs-23.0.94/src/s/cygwin.h	2009-05-14 15:59:41.000000000 -0400
+++ src/emacs-23.0.94/src/s/cygwin.h	2009-06-01 19:06:00.553768000 -0400
@@ -105,11 +105,7 @@ along with GNU Emacs.  If not, see <http
 #define SYSV_SYSTEM_DIR 1
 #define UNEXEC unexcw.o
 #define POSIX_SIGNALS 1
-/* force the emacs image to start high in memory, so dll relocation
-   can put things in low memory without causing all sorts of grief for
-   emacs lisp pointers */
-#define DATA_SEG_BITS 0x20000000
-#define LINKER $(CC) -Wl,--image-base,DATA_SEG_BITS
+#define LINKER $(CC)
 
 /* Use terminfo instead of termcap.  Fewer environment variables to
    go wrong, more terminal types. */