Document problems with rebasing Cygwin DLLs.

diff --git a/etc/PROBLEMS b/etc/PROBLEMS
index c5d0db971c900a7082fc3f698b551ca2376a5a5e..7931212fa796d68097db3945fce5f049e405260e 100644 (file)
--- a/etc/PROBLEMS
+++ b/etc/PROBLEMS
@@ -2115,6 +2115,34 @@ and Shift, the Alt and Shift act as modifiers in the usual way.  A
 more permanent work around is to change it to another key combination,
 or disable it in the keyboard control panel.
 
+** 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