Clarify doc for .arch/.cpu

Documentation for .arch and .cpu directives currently says that it
accepts the same name as -march/-mcpu command-line options respectively.
However it only accept the architecture/CPU part of those options: it
does not accept specifying an extension which is done via
.arch_extension. This patch clarifies that the extension is not
accepted.

2018-07-25  Thomas Preud'homme  <thomas.preudhomme@linaro.org>

gas/
	* doc/c-arm.texi (.arch directive): Clarify that name must not include
	an extension.
	(.cpu directive): Likewise.

1 files changed, 4 insertions, 2 deletions

diff --git a/gas/doc/c-arm.texi b/gas/doc/c-arm.texi
index d2f6fe1..a316c26 100644
--- a/gas/doc/c-arm.texi
+++ b/gas/doc/c-arm.texi
@@ -624,7 +624,8 @@ boundary).  This is for compatibility with ARM's own assembler.
 @cindex @code{.arch} directive, ARM
 @item .arch @var{name}
 Select the target architecture.  Valid values for @var{name} are the same as
-for the @option{-march} command-line option.
+for the @option{-march} command-line option without the instruction set
+extension.
 
 Specifying @code{.arch} clears any previously selected architecture
 extensions.
@@ -663,7 +664,8 @@ selects Thumb, with the value 32 selecting ARM.
 @cindex @code{.cpu} directive, ARM
 @item .cpu @var{name}
 Select the target processor.  Valid values for @var{name} are the same as
-for the @option{-mcpu} command-line option.
+for the @option{-mcpu} command-line option without the instruction set
+extension.
 
 Specifying @code{.cpu} clears any previously selected architecture
 extensions.