Clean up the passing of the boot command line to the kernel.

kern/linux/linux_system.cc:
    Don't hard code the address of the command line in the kernel,
    instead, deduce it from the location of known symbols.
    don't use strcpy, it's dangerous.
kern/linux/linux_system.hh:
    Don't hard code the address of the command line in the kernel,
    instead, deduce it from the location of known symbols.

--HG--
extra : convert_revision : 128b1d5dbd00b0b8571707da99f86f76e29abfd1

kern/linux/linux_system.cc

@@ -52,6 +52,24 @@ LinuxSystem::LinuxSystem(Params *p)
     : System(p)
 {
     Addr addr = 0;
+    Addr paddr = 0;
+
+    /**
+     * The symbol swapper_pg_dir marks the beginning of the kernel and
+     * the location of bootloader passed arguments
+     */
+    if (!kernelSymtab->findAddress("swapper_pg_dir", KernelStart)) {
+        panic("Could not determine start location of kernel");
+    }
+
+    /**
+     * Since we aren't using a bootloader, we have to copy the
+     * kernel arguments directly into the kernel's memory.
+     */
+    paddr = vtophys(physmem, CommandLine());
+    char *commandline = (char *)physmem->dma_addr(paddr, sizeof(uint64_t));
+    if (commandline)
+        strncpy(commandline, params->boot_osflags.c_str(), CommandLineSize);
 
     /**
      * find the address of the est_cycle_freq variable and insert it
@@ -59,7 +77,7 @@ LinuxSystem::LinuxSystem(Params *p)
      * calculated it by using the PIT, RTC, etc.
      */
     if (kernelSymtab->findAddress("est_cycle_freq", addr)) {
-        Addr paddr = vtophys(physmem, addr);
+        paddr = vtophys(physmem, addr);
         uint8_t *est_cycle_frequency =
             physmem->dma_addr(paddr, sizeof(uint64_t));
 
@@ -69,18 +87,6 @@ LinuxSystem::LinuxSystem(Params *p)
     }
 
 
-    /**
-     * Since we aren't using a bootloader, we have to copy the kernel arguments
-     * directly into the kernels memory.
-     */
-    {
-        Addr paddr = vtophys(physmem, PARAM_ADDR);
-        char *commandline = (char*)physmem->dma_addr(paddr, sizeof(uint64_t));
-        if (commandline)
-            strcpy(commandline, params->boot_osflags.c_str());
-    }
-
-
     /**
      * EV5 only supports 127 ASNs so we are going to tell the kernel that the
      * paritiuclar EV6 we have only supports 127 asns.
@@ -88,7 +94,7 @@ LinuxSystem::LinuxSystem(Params *p)
      * 255 ASNs.
      */
     if (kernelSymtab->findAddress("dp264_mv", addr)) {
-        Addr paddr = vtophys(physmem, addr);
+        paddr = vtophys(physmem, addr);
         char *dp264_mv = (char *)physmem->dma_addr(paddr, sizeof(uint64_t));
 
         if (dp264_mv) {

kern/linux/linux_system.hh

@@ -29,12 +29,6 @@
 #ifndef __KERN_LINUX_LINUX_SYSTEM_HH__
 #define __KERN_LINUX_LINUX_SYSTEM_HH__
 
-/**
- * MAGIC address where the kernel arguments should go. Defined as
- * PARAM in linux kernel alpha-asm.
- */
-const Addr PARAM_ADDR = ULL(0xfffffc000030a000);
-
 class ExecContext;
 
 class BreakPCEvent;
@@ -52,6 +46,26 @@ class PrintThreadInfo;
  */
 class LinuxSystem : public System
 {
+  private:
+    /**
+     * Addresses defining where the kernel bootloader places various
+     * elements.  Details found in include/asm-alpha/system.h
+     */
+    Addr KernelStart; // Lookup the symbol swapper_pg_dir
+
+  public:
+    Addr InitStack() const { return KernelStart + 0x02000; }
+    Addr EmptyPGT() const  { return KernelStart + 0x04000; }
+    Addr EmptyPGE() const  { return KernelStart + 0x08000; }
+    Addr ZeroPGE() const   { return KernelStart + 0x0A000; }
+    Addr StartAddr() const { return KernelStart + 0x10000; }
+
+    Addr Param() const { return ZeroPGE() + 0x0; }
+    Addr CommandLine() const { return Param() + 0x0; }
+    Addr InitrdStart() const { return Param() + 0x100; }
+    Addr InitrdSize() const { return Param() + 0x108; }
+    static const int CommandLineSize = 256;
+
   private:
 #ifndef NDEBUG
     /** Event to halt the simulator if the kernel calls panic()  */