arch: Resurrect the NOISA build target and rename it NULL

This patch makes it possible to once again build gem5 without any
ISA. The main purpose is to enable work around the interconnect and
memory system without having to build any CPU models or device models.

The regress script is updated to include the NULL ISA target. Currently
no regressions make use of it, but all the testers could (and perhaps
should) transition to it.

--HG--
rename : build_opts/NOISA => build_opts/NULL
rename : src/arch/noisa/SConsopts => src/arch/null/SConsopts
rename : src/arch/noisa/cpu_dummy.hh => src/arch/null/cpu_dummy.hh
rename : src/cpu/intr_control.cc => src/cpu/intr_control_noisa.cc

3 files changed, 65 insertions, 2 deletions

diff --git a/src/cpu/SConscript b/src/cpu/SConscript
index c52dbc53b..999de1e49 100644
--- a/src/cpu/SConscript
+++ b/src/cpu/SConscript
@@ -30,7 +30,9 @@
 
 Import('*')
 
-if env['TARGET_ISA'] == 'no':
+if env['TARGET_ISA'] == 'null':
+    SimObject('IntrControl.py')
+    Source('intr_control_noisa.cc')
     Return()
 
 #################################################################
diff --git a/src/cpu/base.hh b/src/cpu/base.hh
index 9e7198763..540c72833 100644
--- a/src/cpu/base.hh
+++ b/src/cpu/base.hh
@@ -48,11 +48,16 @@
 
 #include <vector>
 
+// Before we do anything else, check if this build is the NULL ISA,
+// and if so stop here
+#include "config/the_isa.hh"
+#if THE_ISA == NULL_ISA
+#include "arch/null/cpu_dummy.hh"
+#else
 #include "arch/interrupts.hh"
 #include "arch/isa_traits.hh"
 #include "arch/microcode_rom.hh"
 #include "base/statistics.hh"
-#include "config/the_isa.hh"
 #include "mem/mem_object.hh"
 #include "sim/eventq.hh"
 #include "sim/full_system.hh"
@@ -476,4 +481,6 @@ class BaseCPU : public MemObject
     Stats::Scalar numWorkItemsCompleted;
 };
 
+#endif // THE_ISA == NULL_ISA
+
 #endif // __CPU_BASE_HH__
diff --git a/src/cpu/intr_control_noisa.cc b/src/cpu/intr_control_noisa.cc
new file mode 100644
index 000000000..ff49976d0
--- /dev/null
+++ b/src/cpu/intr_control_noisa.cc
@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2002-2005 The Regents of The University of Michigan
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Authors: Nathan Binkert
+ *          Ron Dreslinski
+ */
+
+#include "cpu/intr_control.hh"
+
+using namespace std;
+
+IntrControl::IntrControl(const Params *p)
+    : SimObject(p), sys(p->sys)
+{}
+
+void
+IntrControl::post(int cpu_id, int int_num, int index)
+{
+}
+
+void
+IntrControl::clear(int cpu_id, int int_num, int index)
+{
+}
+
+IntrControl *
+IntrControlParams::create()
+{
+    return new IntrControl(this);
+}