Add CROSS-COMPILE.md, rm CLA link

CONTRIBUTING.md

@@ -1,18 +1,13 @@
-# Contributing
+# Contributing guidelines
 
 If you would like to contribute code to ghostunnel you can do so through GitHub
 by forking the repository and sending a pull request.
 
-When submitting code, please make every effort to follow existing conventions
-and style in order to keep the code as readable as possible. Please also make
-sure all tests pass by running `make test`, and format your code with `go fmt`.
+When submitting code, please make efforts to follow existing conventions and
+style in order to keep the code as readable as possible. Please also make sure
+all tests pass by running `make test`, and format your code with `go fmt`.
 
 Note that ghostunnel relies heavily on integration tests written in Python that
-run checks on a live instance. If you are adding new features or changing 
-existing behavior, please add/update the integration tests in the tests directory
-accordingly.
-
-Before your code can be accepted into the project you must also sign the
-[Individual Contributor License Agreement][1].
-
- [1]: https://spreadsheets.google.com/spreadsheet/viewform?formkey=dDViT2xzUHAwRkI3X3k5Z0lQM091OGc6MQ&ndplr=1
+run checks on a live instance. If you are adding new features or changing
+existing behavior, please add/update the integration tests in the tests
+directory accordingly.

CROSS-COMPILE.md

@@ -0,0 +1,24 @@
+# Instructions for cross-compiling
+
+Ghostunnel has support for loading private keys from PKCS#11 modules, which
+should work with any hardware security module that exposes a PKCS#11 interface.
+A working CGO toolchain is required in order to compile with PKCS#11 support
+enabled.
+
+One way to cross-compile ghostunnel is with [karalabe/xgo][xgo]. Note that
+libtool is a required build dependency, and libltdl needs to be available at
+runtime. You can build a static binary to avoid the libltdl runtime dependency
+by passing appropriate ldflags to the compiler. 
+
+For example, to build a static 64-bit Windows binary:
+
+    xgo \
+      -deps https://ftp.gnu.org/pub/gnu/libtool/libtool-2.4.6.tar.gz \
+      -branch master \
+      -targets 'windows/amd64' \
+      -ldflags "-w -extldflags \"-static\" -extld x86_64-w64-mingw32-gcc" \
+      github.com/square/ghostunnel
+
+For more info, see [xgo][xgo]'s README on GitHub.
+
+[xgo]: https://github.com/karalabe/xgo

README.md

@@ -86,11 +86,10 @@ To run tests:
     # Open coverage information in browser
     go tool cover -html coverage-merged.out
 
-For more information on how to contribute, please see the [CONTRIBUTING][contr] file.
+For more information on how to contribute, please see the [CONTRIBUTING](CONTRIBUTING.md) file.
 
 [gvt]: https://github.com/FiloSottile/gvt
 [gcvm]: https://github.com/wadey/gocovmerge
-[contr]: https://github.com/square/ghostunnel/blob/master/CONTRIBUTING.md
 
 Usage Examples
 ==============
@@ -248,11 +247,12 @@ For information on profiling via pprof, see the
 
 ### HSM/PKCS#11 support
 
-Ghostunnel has experimental support for loading private keys from PKCS#11
-modules, which should work with any hardware security module that exposes a
-PKCS#11 interface. An easy way to test the PKCS#11 interface for development
-purposes is with [SoftHSM][softhsm]. Note that CGO is required in order for
-PKCS#11 support to work.
+Ghostunnel has support for loading private keys from PKCS#11 modules, which
+should work with any hardware security module that exposes a PKCS#11 interface.
+An easy way to test the PKCS#11 interface for development purposes is with
+[SoftHSM][softhsm]. Note that CGO is required in order for PKCS#11 support to
+work (see [CROSS-COMPILE.md](CROSS-COMPILE.md) for instructions to
+cross-compile with CGO enabled).
 
 [softhsm]: https://github.com/opendnssec/SoftHSMv2