doc: update for RI.6

- change default compiler from xt-xcc to xt-clang;
- update tested/supported linux kernel versions;
- update cover and list of changes.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

Author: jcmvbkbc

doc/preface.dox

@@ -35,12 +35,10 @@
 ///  Changes from the Previous Version
 ///  ---------------------------------
 ///  
-///  The following changes were made to this document for the Cadence RI-2019.1
+///  The following changes were made to this document for the Cadence RI-2021.6
 ///  release of Xtensa processors. Subsequent releases may contain updates for
 ///  features in this release or additional features may be added.
 ///  
-///  * New chapter \ref features is added and the chapter \ref features_operation
-///    is now a section inside this chapter.
-///  * New section \ref features_multiqueue is added to the \ref features chapter.
-///  * Information about the new `simple-xos` port is added to the
-///    \ref building_libraries chapter.
+///  * Range of tested and supported linux kernel versions is updated.
+///  * configure script invocation examples are updated to reflect new example
+///    directories layout, subsystem parameters and default compiler choice.

doc/title.tex

@@ -159,7 +159,7 @@
 OSCI, SystemC, Open SystemC, Open SystemC Initiative, and SystemC Initiative are registered trademarks of Open SystemC Initiative, Inc. in the United States and other countries and are used with permission. All other trademarks are the property of their respective holders.
 \vspace*{2.5cm}
 \newline Issue Date: \twodigits{\the\month}/{\the\year}
-\newline RI-2019.3
+\newline RI-2021.6
 \vspace*{0.4cm}
 \newline
 \vspace*{0.5cm}

doc/xrp_user_guide.dox

@@ -102,7 +102,7 @@ work on a very broad range of Xtensa cores. It is tested with Xtensa
 software versions RF.5 and later.
 
 The Linux kernel driver is tested with a number of Linux kernel versions from
-3.18 to 5.3 and is known to work on Xtensa, 32- and 64-bit ARM and x86 Linux.
+3.18 to 5.4 and is known to work on Xtensa, 32- and 64-bit ARM and x86 Linux.
 
 The driver makes the following assumptions:
 - The DSP has the same endianness as the host.
@@ -1041,7 +1041,7 @@ variable to the `configure` or to `make`:
   for xtensa:
 
 <pre>
-  $ ./configure --host=xtensa-elf CC=xt-xcc
+  $ ./configure --host=xtensa-elf CC=xt-clang
   $ make
 </pre>
 
@@ -1091,7 +1091,7 @@ binary may be used with `configure` or `make` command.
   $ ./configure --host=xtensa-elf --disable-host --disable-standalone \
     --enable-example \
     DSP_LSP=vp6-mp/package/cores/DSP_0/xtensa-elf/lib/sim-stacklocal \
-    CC='xt-xcc --xtensa-core=visionp6_ao'
+    CC='xt-clang --xtensa-core=visionp6_ao'
   $ make
 </pre>
 
@@ -1112,7 +1112,7 @@ binary may be used with `configure` or `make` command.
     --enable-standalone --enable-example \
     DSP_LSP=vp6-mp/package/cores/DSP_0/xtensa-elf/lib/sim-stacklocal \
     DSP_COMM_BASE=0x10000000 \
-    CC='xt-xcc --xtensa-core=visionp6_ao'
+    CC='xt-clang --xtensa-core=visionp6_ao'
   $ make
 </pre>
 
@@ -1141,7 +1141,7 @@ binary may be used with `configure` or `make` command.
   - `HOST_CACHEATTR`: value for the `_memmap_cacheattr_reset` symbol.
 
 <pre>
-  $ ./configure --host=xtensa-elf CC=xt-xcc --enable-example
+  $ ./configure --host=xtensa-elf CC=xt-clang --enable-example
   $ make
 </pre>