1 files changed, 25 insertions, 0 deletions
diff --git a/src/cmd/cgo/doc.go b/src/cmd/cgo/doc.go
index 022a87c15..0f9204d7f 100644
--- a/src/cmd/cgo/doc.go
+++ b/src/cmd/cgo/doc.go
@@ -23,6 +23,31 @@ the package.  For example:
 	// #include <errno.h>
 	import "C"
 
+C identifiers or field names that are keywords in Go can be
+accessed by prefixing them with an underscore: if x points at
+a C struct with a field named "type", x._type accesses the field.
+
+The standard C numeric types are available under the names
+C.char, C.schar (signed char), C.uchar (unsigned char),
+C.short, C.ushort (unsigned short), C.int, C.uint (unsigned int),
+C.long, C.ulong (unsigned long), C.longlong (long long),
+C.ulonglong (unsigned long long), C.float, C.double.
+
+To access a struct, union, or enum type directly, prefix it with
+struct_, union_, or enum_, as in C.struct_stat.
+
+Any C function that returns a value may be called in a multiple
+assignment context to retrieve both the return value and the
+C errno variable as an os.Error.  For example:
+
+	n, err := C.atoi("abc")
+
+In C, a function argument written as a fixed size array
+actually requires a pointer to the first element of the array.
+C compilers are aware of this calling convention and adjust
+the call accordingly, but Go cannot.  In Go, you must pass
+the pointer to the first element explicitly: C.f(&x[0]).
+
 Cgo transforms the input file into four output files: two Go source
 files, a C file for 6c (or 8c or 5c), and a C file for gcc.