X-Git-Url: https://vcs.fsf.org/?a=blobdiff_plain;f=doc%2Fdoc-txt%2Fopenssl.txt;h=7bcd47907402b1e055ae26fc970a091108fda6fb;hb=bb264f6b766cd2c51afad224c9b047705937e69e;hp=e4f5d854cfb054b650520f4f935226f8fe7a5689;hpb=1922a912d23fc06ee7fb0d22d9cf3e633a4713dc;p=exim.git

diff --git a/doc/doc-txt/openssl.txt b/doc/doc-txt/openssl.txt
index e4f5d854c..7bcd47907 100644
--- a/doc/doc-txt/openssl.txt
+++ b/doc/doc-txt/openssl.txt
@@ -36,12 +36,23 @@ Extract the current source of OpenSSL.  Change into that directory.
 This assumes that `/opt/openssl` is not in use.  If it is, pick
 something else.  `/opt/exim/openssl` perhaps.
 
+If you pick a location shared amongst various local packages, such as
+`/usr/local` on Linux, then the new OpenSSL will be used by all of those
+packages.  If that's what you want, great!  If instead you want to
+ensure that only software you explicitly set to use the newer OpenSSL
+will try to use the new OpenSSL, then stick to something like
+`/opt/openssl`.
+
     ./config --prefix=/opt/openssl --openssldir=/etc/ssl  \
         -L/opt/openssl/lib -Wl,-R/opt/openssl/lib         \
         enable-ssl-trace shared
     make
     make install
 
+On some systems, the linker uses `-rpath` instead of `-R`; on such systems,
+replace the parameter starting `-Wl` with: `-Wl,-rpath,/opt/openssl/lib`.
+There are more variations on less common systems.
+
 You now have an installed OpenSSL under /opt/openssl which will not be
 used by any system programs.
 
@@ -94,6 +105,22 @@ is to run:
 
     readelf -d $(which exim) | grep RPATH
 
+It is important to use `RPATH` and not `RUNPATH`!
+
+The gory details about `RUNPATH` (skip unless interested):
+The OpenSSL library might be opened indirectly by some other library
+which Exim depends upon.  If the executable does have `RUNPATH` then
+that will inhibit using either of `RPATH` or `RUNPATH` from the
+executable for finding the OpenSSL library when that other library tries
+to load it.
+In fact, if the intermediate library has a `RUNPATH` stamped into it,
+then this will block `RPATH` too, and will create problems with Exim.
+If you're in such a situation, and those libraries were supplied to you
+instead of built by you, then you're reaching the limits of sane
+repairability and it's time to prioritize rebuilding your mail-server
+hosts to be a current OS release which natively pulls in an
+upstream-supported OpenSSL, or stick to the OS releases of Exim.
+
 
 Very Advanced
 -------------