doc/install: describe GOHOSTOS and GOHOSTARCH

Fixes #1303.

R=rsc, PeterGo
CC=golang-dev
https://golang.org/cl/3442041

diff --git a/doc/install.html b/doc/install.html
index be1131d4aa7b95c193475e2e1b8d23de5418a551..510464960f94aa04551fe551ebbd5025d478cb38 100644 (file)
--- a/doc/install.html
+++ b/doc/install.html
@@ -297,7 +297,7 @@ that receives a message summarizing each checkin to the Go repository.
 <h2 id="environment">Environment variables</h2>
 
 <p>
-The Go compilation environment can be customized by five environment variables.
+The Go compilation environment can be customized by environment variables.
 None are required by the build, but you may wish to set them
 to override the defaults.
 </p>
@@ -331,8 +331,8 @@ to override the defaults.
 </dt>
 <dd>
        The name of the target operating system and compilation architecture.
-       These default to the local system's operating system and
-       architecture.
+       These default to the values of <code>$GOHOSTOS</code> and
+       <code>$GOHOSTARCH</code> respectively (described below).
 
        <p>
        Choices for <code>$GOOS</code> are <code>linux</code>,
@@ -377,6 +377,22 @@ to override the defaults.
        </table>
 </dd>
 
+<dt>
+<code>$GOHOSTOS</code> and <code>$GOHOSTARCH</code>
+</dt>
+<dd>
+       The name of the host operating system and compilation architecture.
+       These default to the local system's operating system and
+       architecture.
+
+       <p>
+       Valid choices are the same as for <code>$GOOS</code> and
+       <code>$GOARCH</code>, listed above.
+       The specified values must be compatible with the local system.
+       For example, you should not set <code>$GOHOSTARCH</code> to 
+       <code>arm</code> on an x86 system.
+</dd>
+
 <dt>
 <code>$GOBIN</code>
 </dt>