chachap10-ppc.pl: Fix truncated relocation

[openssl.git] / INSTALL.md

diff --git a/INSTALL.md b/INSTALL.md
index d17dc7bc8ebee5766588247269a5ce9430c6e4bd..95842c4641e647eec54851c74113e9e20c0c24ff 100644 (file)
--- a/INSTALL.md
+++ b/INSTALL.md
@@ -2,8 +2,8 @@ Build and Install
 =================
 
 This document describes installation on all supported operating
-systems (the Unix/Linux family, including macOS), OpenVMS,
-and Windows).
+systems: the Unix/Linux family (including macOS), OpenVMS,
+and Windows.
 
 Table of Contents
 =================
@@ -547,6 +547,13 @@ be used even with this option.
 
 Do not build support for async operations.
 
+### no-atexit
+
+Do not use `atexit()` in libcrypto builds.
+
+`atexit()` has varied semantics between platforms and can cause SIGSEGV in some
+circumstances. This option disables the atexit registration of OPENSSL_cleanup.
+
 ### no-autoalginit
 
 Don't automatically load all supported ciphers and digests.
@@ -797,14 +804,22 @@ By default OpenSSL will attempt to stay in memory until the process exits.
 This is so that libcrypto and libssl can be properly cleaned up automatically
 via an `atexit()` handler.  The handler is registered by libcrypto and cleans
 up both libraries.  On some platforms the `atexit()` handler will run on unload of
-libcrypto (if it has been dynamically loaded) rather than at process exit.  This
-option can be used to stop OpenSSL from attempting to stay in memory until the
+libcrypto (if it has been dynamically loaded) rather than at process exit.
+
+This option can be used to stop OpenSSL from attempting to stay in memory until the
 process exits.  This could lead to crashes if either libcrypto or libssl have
 already been unloaded at the point that the atexit handler is invoked, e.g.  on a
 platform which calls `atexit()` on unload of the library, and libssl is unloaded
-before libcrypto then a crash is likely to happen.  Applications can suppress
-running of the `atexit()` handler at run time by using the
-`OPENSSL_INIT_NO_ATEXIT` option to `OPENSSL_init_crypto()`.
+before libcrypto then a crash is likely to happen.
+
+Note that shared library pinning is not automatically disabled for static builds,
+i.e., `no-shared` does not imply `no-pinshared`. This may come as a surprise when
+linking libcrypto statically into a shared third-party library, because in this
+case the shared library will be pinned. To prevent this behaviour, you need to
+configure the static build using `no-shared` and `no-pinshared` together.
+
+Applications can suppress running of the `atexit()` handler at run time by
+using the `OPENSSL_INIT_NO_ATEXIT` option to `OPENSSL_init_crypto()`.
 See the man page for it for further details.
 
 ### no-posix-io
@@ -1204,6 +1219,14 @@ and `descrip.mms` on OpenVMS) from a suitable template in `Configurations/`,
 and defines various macros in `include/openssl/configuration.h` (generated
 from `include/openssl/configuration.h.in`.
 
+If none of the generated build files suit your purpose, it's possible to
+write your own build file template and give its name through the environment
+variable `BUILDFILE`.  For example, Ninja build files could be supported by
+writing `Configurations/build.ninja.tmpl` and then configure with `BUILDFILE`
+set like this (Unix syntax shown, you'll have to adapt for other platforms):
+
+    $ BUILDFILE=build.ninja perl Configure [options...]
+
 ### Out of Tree Builds
 
 OpenSSL can be configured to build in a build directory separate from the