Provide documentation for auto-init/auto-deinit

[openssl.git] / INSTALL.WIN

diff --git a/INSTALL.WIN b/INSTALL.WIN
index d57923886c59dc46483f2bd43b5d12161844e735..ceb8d1ee39d36dd6ea993c5e7bc00a73a1e220a2 100644 (file)
--- a/INSTALL.WIN
+++ b/INSTALL.WIN
@@ -190,3 +190,19 @@
  your application code small "shim" snippet, which provides glue between
  OpenSSL BIO layer and your compiler run-time. See the OPENSSL_Applink
  manual page for further details.
+
+ Support for older Windows platforms
+ -----------------------------------
+
+ By default OpenSSL will use functions and capabilities of the Windows platform
+ only available in Windows Vista, Windows Server 2008 or later. It is possible
+ to enable support for older platforms by defining _WIN32_WINNT at Configure
+ time.
+
+  > perl Configure VC-WIN32 --prefix=c:\some\openssl\dir -D_WIN32_WINNT=0x0501
+
+ The value 0x0501 above corresponds to Windows XP which is the oldest supported
+ platform. The value 0x0600 corresponds to Windows Vista and Windows Server
+ 2008. Refer to the Windows documentation for other possible values. Note that
+ by forcing support for an older OpenSSL version this may mean less optimal
+ approaches are used instead.