sim: Add an option to load additional kernel objects

There are cases where it is desirable to load a kernel and a set of
additional objects. This can, for example, be useful for testing where
the bootstrap code can be loaded from one object (the kernel) and the
test proper from another.

This changeset adds this functionality by adding a kernel_extras
vector parameter to the System class. Object files in this vector are
loaded in order after the kernel when running in full system mode.

Change-Id: I06f57c6a65a17b02eb4267bed0aa829f21bcfa3b
Reviewed-on: https://gem5-review.googlesource.com/5703
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>

src/sim/System.py

@@ -93,6 +93,7 @@ class System(MemObject):
     kernel = Param.String("", "file that contains the kernel code")
     kernel_addr_check = Param.Bool(True,
         "whether to address check on kernel (disable for baremetal)")
+    kernel_extras = VectorParam.String([],"Additional object files to load")
     readfile = Param.String("", "file to read startup script from")
     symbolfile = Param.String("", "file to get the symbols from")
     load_addr_mask = Param.UInt64(0xffffffffff,

src/sim/system.cc

@@ -174,6 +174,14 @@ System::System(Params *p)
             // Loading only needs to happen once and after memory system is
             // connected so it will happen in initState()
         }
+
+        for (const auto &obj_name : p->kernel_extras) {
+            inform("Loading additional kernel object: %s", obj_name);
+            ObjectFile *obj = createObjectFile(obj_name);
+            fatal_if(!obj, "Failed to additional kernel object '%s'.\n",
+                     obj_name);
+            kernelExtras.push_back(obj);
+        }
     }
 
     // increment the number of running systems
@@ -312,6 +320,10 @@ System::initState()
             }
             // Load program sections into memory
             kernel->loadSections(physProxy, loadAddrMask, loadAddrOffset);
+            for (const auto &extra_kernel : kernelExtras) {
+                extra_kernel->loadSections(physProxy, loadAddrMask,
+                                           loadAddrOffset);
+            }
 
             DPRINTF(Loader, "Kernel start = %#x\n", kernelStart);
             DPRINTF(Loader, "Kernel end   = %#x\n", kernelEnd);

src/sim/system.hh

@@ -229,6 +229,9 @@ class System : public MemObject
     /** Object pointer for the kernel code */
     ObjectFile *kernel;
 
+    /** Additional object files */
+    std::vector<ObjectFile *> kernelExtras;
+
     /** Beginning of kernel code */
     Addr kernelStart;