Index: README.INSTALL
===================================================================
--- README.INSTALL	(revision 927)
+++ README.INSTALL	(working copy)
@@ -74,6 +74,19 @@
 Once the target kernel has been prepared, all Xenomai configuration
 options are available from the "Real-time subsystem" toplevel menu.
 
+When configuring, you should *disable* PM (power management), ACPI,
+and CPU_FREQ.  The 1st 2 invoke uninterruptible BIOS routines, which
+destroy the rt-determinism guarantees that you're presumably seeking.
+If you're curious, build it, install it, and run xeno-test, you'll
+likely see very large latencies.  If you see otherwise, please email
+the evidence.
+
+CPU_FREQ is bad because it breaks some timing guarantees on some
+chips, and these problems are too varied/unpredictable to accomodate.
+For example, (my) Pentium-M laptop shows "cpu MHz : 600.000" at idle,
+but 1700 when compiling.  Some TSCs also change frequency with the
+processor, making them useless if the clock is changing.
+
 Once configured, the kernel should be built as usual.
 
 It might be a good idea to put all the output into a different build
@@ -143,9 +156,11 @@
 NAME                DESCRIPTION                      [BINDING,]DEFAULT(*)
 
 --enable-x86-sep    Enable x86 SEP instructions      strong,disabled
-                    for issuing syscalls
+                    for issuing syscalls.
+		    You will also need NPTL
 
 --enable-x86-tsc    Enable x86 TSC for timings       strong,enabled
+		    falls back to PIT if needed
 
 --enable-arm-arch   Define version of the target     strong,"4"
                     ARM core architecture