Initial support for CPU switching. New SamplingCPU object encompasses a set

of CPUs that get switched round-robin (though currently we're only shooting for
two CPUs and one switch event, and even that doesn't quite work yet).  Registration
of ExecContexts with System/Process object factored out so we can create two CPUs
but only register one of them at a time.  Also worked at making behavior and naming
in System and Process objects more consistent.

arch/alpha/ev5.cc:
    Rename ipr_init to initIPRs and get rid of unused mem arg.
arch/alpha/fake_syscall.cc:
    Process:numCpus is now a function (not a data member).
base/remote_gdb.hh:
    Support for ExecContext switching.
cpu/base_cpu.cc:
cpu/base_cpu.hh:
cpu/exec_context.cc:
cpu/exec_context.hh:
cpu/simple_cpu/simple_cpu.hh:
    Support for ExecContext switching.
    Renamed contexts array to execContexts to be consistent with Process.
    CPU ID now auto-assigned by system object.
cpu/simple_cpu/simple_cpu.cc:
    Support for ExecContext switching.
    Renamed contexts array to execContexts to be consistent with Process.
    CPU ID now auto-assigned by system object.
    Cleaned up MP full-system initialization a bit.
dev/alpha_console.cc:
    Renamed xcvec array to execContexts to be consistent with Process.
kern/tru64/tru64_system.cc:
kern/tru64/tru64_system.hh:
    Support for ExecContext switching.
    CPU ID now auto-assigned by system object.
sim/prog.cc:
sim/prog.hh:
    Support for ExecContext switching.
    Process:numCpus is now a function (not a data member).
sim/system.cc:
sim/system.hh:
    Support for ExecContext switching.
    Renamed xcvec array to execContexts to be consistent with Process.

--HG--
extra : convert_revision : 79649cffad5bf3e83de8df44236941907926d791

4 files changed, 52 insertions, 30 deletions

diff --git a/sim/prog.cc b/sim/prog.cc
index 275e1551b..599a0ca9a 100644
--- a/sim/prog.cc
+++ b/sim/prog.cc
@@ -85,8 +85,6 @@ Process::Process(const string &name,
         fd_map[i] = -1;
     }
 
-    numCpus = 0;
-
     num_syscalls = 0;
 
     // other parameters will be initialized when the program is loaded
@@ -136,30 +134,42 @@ Process::openOutputFile(const string &filename)
 }
 
 
-void
-Process::registerExecContext(ExecContext *ec)
+int
+Process::registerExecContext(ExecContext *xc)
 {
-    if (execContexts.empty()) {
+    // add to list
+    int myIndex = execContexts.size();
+    execContexts.push_back(xc);
+
+    if (myIndex == 0) {
         // first exec context for this process... initialize & enable
 
         // copy process's initial regs struct
-        ec->regs = *init_regs;
+        xc->regs = *init_regs;
 
         // mark this context as active
-        ec->setStatus(ExecContext::Active);
+        xc->initStatus(ExecContext::Active);
     }
     else {
-        ec->setStatus(ExecContext::Unallocated);
+        xc->initStatus(ExecContext::Unallocated);
     }
 
-    // add to list
-    execContexts.push_back(ec);
-
-    // increment available CPU count
-    ++numCpus;
+    // return CPU number to caller and increment available CPU count
+    return myIndex;
 }
 
 
+void
+Process::replaceExecContext(int xcIndex, ExecContext *xc)
+{
+    if (xcIndex >= execContexts.size()) {
+        panic("replaceExecContext: bad xcIndex, %d >= %d\n",
+              xcIndex, execContexts.size());
+    }
+
+    execContexts[xcIndex] = xc;
+}
+
 // map simulator fd sim_fd to target fd tgt_fd
 void
 Process::dup_fd(int sim_fd, int tgt_fd)
diff --git a/sim/prog.hh b/sim/prog.hh
index ee4bc59fe..e93dd684c 100644
--- a/sim/prog.hh
+++ b/sim/prog.hh
@@ -36,7 +36,7 @@
 //
 #ifndef FULL_SYSTEM
 
-#include <list>
+#include <vector>
 
 #include "targetarch/isa_traits.hh"
 #include "sim/sim_object.hh"
@@ -55,10 +55,10 @@ class Process : public SimObject
     bool initialContextLoaded;
 
     // execution contexts associated with this process
-    std::list<ExecContext *> execContexts;
-    // number of CPUs assigned to this process: should match number of
-    // contexts in execContexts list
-    unsigned numCpus;
+    std::vector<ExecContext *> execContexts;
+
+    // number of CPUs (esxec contexts, really) assigned to this process.
+    unsigned int numCpus() { return execContexts.size(); }
 
     // record of blocked context
     struct WaitRec
@@ -123,8 +123,12 @@ class Process : public SimObject
     // override of virtual SimObject method: register statistics
     virtual void regStats();
 
-    // register an execution context for this process
-    void registerExecContext(ExecContext *);
+    // register an execution context for this process.
+    // returns xc's cpu number (index into execContexts[])
+    int registerExecContext(ExecContext *xc);
+
+
+    void replaceExecContext(int xcIndex, ExecContext *xc);
 
     // map simulator fd sim_fd to target fd tgt_fd
     void dup_fd(int sim_fd, int tgt_fd);
diff --git a/sim/system.cc b/sim/system.cc
index 0e0b83332..76c895a88 100644
--- a/sim/system.cc
+++ b/sim/system.cc
@@ -56,16 +56,24 @@ System::~System()
 }
 
 
-void
+int
 System::registerExecContext(ExecContext *xc)
 {
-    if (xc->cpu_id >= 12/*MAX_CPUS*/)
-        panic("Too many CPU's\n");
+    int myIndex = execContexts.size();
+    execContexts.push_back(xc);
+    return myIndex;
+}
+
 
-    if (xc->cpu_id >= xcvec.size())
-        xcvec.resize(xc->cpu_id + 1);
+void
+System::replaceExecContext(int xcIndex, ExecContext *xc)
+{
+    if (xcIndex >= execContexts.size()) {
+        panic("replaceExecContext: bad xcIndex, %d >= %d\n",
+              xcIndex, execContexts.size());
+    }
 
-    xcvec[xc->cpu_id] = xc;
+    execContexts[xcIndex] = xc;
 }
 
 
diff --git a/sim/system.hh b/sim/system.hh
index 56a3d6a6f..1c4440b9a 100644
--- a/sim/system.hh
+++ b/sim/system.hh
@@ -52,16 +52,16 @@ class System : public SimObject
 
     PCEventQueue pcEventQueue;
 
-    std::vector<ExecContext *> xcvec;
-    void registerExecContext(ExecContext *xc);
+    std::vector<ExecContext *> execContexts;
+
+    virtual int registerExecContext(ExecContext *xc);
+    virtual void replaceExecContext(int xcIndex, ExecContext *xc);
 
   public:
     System(const std::string _name, const int _init_param,
            MemoryController *, PhysicalMemory *);
     ~System();
 
-    virtual void init(ExecContext *xc) = 0;
-
     virtual Addr getKernelStart() const = 0;
     virtual Addr getKernelEnd() const = 0;
     virtual Addr getKernelEntry() const = 0;