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+/*
+ * Copyright (c) 2001-2005 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
+ */
+
+/** @file
+ * System Console Backdoor Interface
+ */
+
+#ifndef __DEV_ALPHA_BACKDOOR_HH__
+#define __DEV_ALPHA_BACKDOOR_HH__
+
+#include "base/range.hh"
+#include "dev/alpha/access.h"
+#include "dev/io_device.hh"
+#include "params/AlphaBackdoor.hh"
+#include "sim/host.hh"
+#include "sim/sim_object.hh"
+
+class BaseCPU;
+class Terminal;
+class AlphaSystem;
+class SimpleDisk;
+
+/**
+ * Memory mapped interface to the system console. This device
+ * represents a shared data region between the OS Kernel and the
+ * System Console Backdoor.
+ *
+ * The system console is a small standalone program that is initially
+ * run when the system boots.  It contains the necessary code to
+ * access the boot disk, to read/write from the console, and to pass
+ * boot parameters to the kernel.
+ *
+ * This version of the system console is very different from the one
+ * that would be found in a real system.  Many of the functions use
+ * some sort of backdoor to get their job done.  For example, reading
+ * from the boot device on a real system would require a minimal
+ * device driver to access the disk controller, but since we have a
+ * simulator here, we are able to bypass the disk controller and
+ * access the disk image directly.  There are also some things like
+ * reading the kernel off the disk image into memory that are normally
+ * taken care of by the console that are now taken care of by the
+ * simulator.
+ *
+ * These shortcuts are acceptable since the system console is
+ * primarily used doing boot before the kernel has loaded its device
+ * drivers.
+ */
+class AlphaBackdoor : public BasicPioDevice
+{
+  protected:
+    struct Access : public AlphaAccess
+    {
+        void serialize(std::ostream &os);
+        void unserialize(Checkpoint *cp, const std::string &section);
+    };
+
+    union {
+        Access *alphaAccess;
+        uint8_t *consoleData;
+    };
+
+    /** the disk must be accessed from the console */
+    SimpleDisk *disk;
+
+    /** the system console (the terminal) is accessable from the console */
+    Terminal *terminal;
+
+    /** a pointer to the system we are running in */
+    AlphaSystem *system;
+
+    /** a pointer to the CPU boot cpu */
+    BaseCPU *cpu;
+
+  public:
+    typedef AlphaBackdoorParams Params;
+    AlphaBackdoor(const Params *p);
+
+    const Params *
+    params() const
+    {
+        return dynamic_cast<const Params *>(_params);
+    }
+
+    virtual void startup();
+
+    /**
+     * memory mapped reads and writes
+     */
+    virtual Tick read(PacketPtr pkt);
+    virtual Tick write(PacketPtr pkt);
+
+    /**
+     * standard serialization routines for checkpointing
+     */
+    virtual void serialize(std::ostream &os);
+    virtual void unserialize(Checkpoint *cp, const std::string &section);
+};
+
+#endif // __DEV_ALPHA_BACKDOOR_HH__