[m-rev.] diff: Note problems with recent versions of MS Visual Studio and Windows SDK.

[Peter Wang]

README.MS-VisualC:
    As above.
---
 README.MS-VisualC | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/README.MS-VisualC b/README.MS-VisualC
index 2b3f36f60..232a8f724 100644
--- a/README.MS-VisualC
+++ b/README.MS-VisualC
@@ -46,30 +46,36 @@ do the following:
 In order to install the C#, Erlang or Java grades you will require a C#,
 Erlang or Java compiler to be included in the Windows PATH.
 (See the relevant README files for further details, e.g. README.Java etc)
 
 
 *** IMPORTANT NOTE FOR USERS OF VISUAL STUDIO 2013 (OR LATER) ***
 
 The Makefile for the Boehm garbage collector requires the files NtWin32.Mak and
 Win32.Mak to be present in the build environment.  These files are *not*
 included with Visual Studio 2013+ and must be copied or included from the
-Windows SDK.
+Windows SDK.  The last version known to provide those files is the Windows 7.1
+SDK.  The need for those files should go away once we update Boehm GC to
+version 7.6.8 (not yet released).
 
 To include the above files, append the SDK directory to the end of the INCLUDE
 environment variable, for example (with the Windows 7.1 SDK):
 
    C:\> set INCLUDE=%INCLUDE%;C:\Program Files (x86)\Microsoft SDKs\Windows\v7.1a\Include
 
 Alternatively, copy the NtWin32.Mak and Win32.Mak files into the "boehm_gc"
 directory of the Mercury source tree.
 
+Note that boehm_gc/NT_MAKEFILE is hardcoded for the i386 architecture.
+Building for x86_64 will at least require editing of some makefiles.
+This problem can also be resolved once we update Boehm GC to version 7.6.8.
+
 -----------------------------------------------------------------------------
 
 CONFIGURATION AND INSTALLATION
 
 The MSVC port of Mercury is compatible with the prebuilt C files contained in
 the Mercury source distribution.  The 'asm_fast' and 'reg' grades will not work
 with MSVC (see below).  When using the prebuilt C files the compiler will be
 built in the 'hlc.gc.pregen' grade.
 
 Alternatively, if you have an existing Mercury installation that uses the MinGW
-- 
2.18.0