On 05/04/2017 09:39 AM, Jacob Champion wrote:
On 05/04/2017 09:36 AM, William A Rowe Jr wrote:
Ugh... This suggests we've further broken crosscompile, just noticed
this based on your comment.
Why? Cross-compilation uses the same fallback mechanism.
To expand on this, there are three choices for implementation for older
(pre-1.1.0) OpenSSLs:
- Builtin (optimal on some platforms, nonexistent or unsafe on others)
- Deprecated (but believed safe enough for most)
- Dangerous (but still apparently good enough for a bunch of people?)
Builtin is only used if we can *prove* that the builtin implementation
is available and safe. Some environments (Windows + 1.0.x) are known to
have safe builtins; everyone else has to run a test.
If we can't run that test for any reason, we fall back to the Deprecated
implementation. If that API is no longer available (e.g.
OPENSSL_NO_DEPRECATED is in use), we have no choice but to use the
Dangerous implementation.
So since we can't run a test executable on a cross-compile target, if
you're cross-compiling to a platform that isn't "known safe", we'll fall
back to the Deprecated implementation if it's available. That choice can
be overridden with a cachevar, if you know your platform guarantees
safety -- ac_cv_openssl_use_errno_threadid in this case.
--Jacob
