doc: Document DEFAULT BND/NOBND in changes, add use case

Add DEFAULT BND/NOBND to the change history, and explain the use case.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

diff --git a/doc/changes.src b/doc/changes.src
index a366c3f..ba3e7d3 100644 (file)
--- a/doc/changes.src
+++ b/doc/changes.src
@@ -50,6 +50,11 @@ This is expected to be most useful for the MPX instructions.
 
 \b Support \c{BND} prefix for branch instructions (for MPX).
 
+\b The \c{DEFAULT} directive can now take \c{BND} and \c{NOBND}
+options to indicate whether all relevant branches should be getting
+\c{BND} prefixes.  This is expected to be the normal for use in MPX
+code.
+
 \b Add \c{{evex}}, \c{{vex3}} and \c{{vex2}} instruction prefixes to
 have NASM encode the corresponding instruction, if possible, with an EVEX,
 3-byte VEX, or 2-byte VEX prefix, respectively.

diff --git a/doc/nasmdoc.src b/doc/nasmdoc.src
index dbf8e70..55a6313 100644 (file)
--- a/doc/nasmdoc.src
+++ b/doc/nasmdoc.src
@@ -4471,6 +4471,9 @@ be used.
 \c{DEFAULT NOBND} can disable \c{DEFAULT BND} and then \c{BND} prefix will be
 added only when explicitly specified in code.
 
+\c{DEFAULT BND} is expected to be the normal configuration for writing
+MPX-enabled code.
+
 \H{section} \i\c{SECTION} or \i\c{SEGMENT}: Changing and \i{Defining
 Sections}