X-Git-Url: https://git.verplant.org/?a=blobdiff_plain;f=README;h=b639095dc2d316a40c25fe2edb8f01d731a555e8;hb=988688ace2eee6b19595c780ef776785b387f80d;hp=794511c4b8b4402e163c391618ae3df34983ccb3;hpb=e71b0716ca4c0a3df8ffae073d66535a7f61d70e;p=collectd.git

diff --git a/README b/README
index 794511c4..b639095d 100644
--- a/README
+++ b/README
@@ -253,7 +253,7 @@ Prerequisites
 
   * librrd (optional; headers and library; rrdtool 1.0 and 1.2 both work fine)
     If built without `librrd' the resulting binary will be `client only', i.e.
-    will send it's values via multicast and not create any RRD files itself.
+    will send its values via multicast and not create any RRD files itself.
     Alternatively you can chose to write CSV-files (Comma Seperated Values)
     instead.
 
@@ -275,6 +275,26 @@ Prerequisites
     For compiling on Darwin in general and the `apple_sensors' plugin in
     particular.
 
+
+Crosscompiling
+--------------
+
+    To compile correctly collectd needs to be able to initialize static
+    variables to NAN (Not A Number). Some C libraries, especially the GNU
+    libc, have a problem with that.
+
+    Luckily, with GCC it's possible to work around that problem: One can define
+    NAN as being (0.0 / 0.0) and `isnan' as `f != f'. However, to test this
+    ``implementation'' the configure script needs to compile and run a short
+    test program. Obviously running a test program when doing a cross-
+    compilation is, well, challenging.
+
+    If you run into this problem, you can use the `--with-nan-emulation'
+    configure option to force the use of this implementation. We can't promise
+    that the compiled binary actually behaves as it should, but since NANs
+    are likely never passed to the libm you have a good chance to be lucky.
+
+
 Author
 ------