determine amount of memory available

2 files changed, 47 insertions, 1 deletions

diff --git a/atags.c b/atags.c
index 9b88724..e2e6a24 100644
--- a/atags.c
+++ b/atags.c
@@ -38,7 +38,11 @@ uint32_t find_memory_size(struct atag_header *atags)
   // our design assumes address 0x0 is available, so we reject mem
   // atag saying otherwise
   if (mem_tag->start != 0)
-    return 0;
+    {
+      puts("ignoring information about memory, "
+	   "that doesn't start at 0x0");
+      return 0;
+    }
 
   return mem_tag->size;
 }
diff --git a/setup.c b/setup.c
index f0a9d0a..b7c03ad 100644
--- a/setup.c
+++ b/setup.c
@@ -3,6 +3,8 @@
 #include "demo_functionality.h"
 #include "paging.h"
 #include "atags.h"
+// for POWER_OF_2() macro... perhaps the macro should be moved
+#include "memory.h"
 
 void setup(uint32_t r0, uint32_t machine_type,
 	   struct atag_header *atags)
@@ -17,6 +19,8 @@ void setup(uint32_t r0, uint32_t machine_type,
   puts("Hello, kernel World!");
 
   prints("ARM machine type: 0x"); printhext(machine_type); puts("");
+
+  uint32_t memory_size = 0;
   
   // value 3 introduced by stage1 code means no atags was found
   if (r0 == 3)
@@ -31,8 +35,46 @@ void setup(uint32_t r0, uint32_t machine_type,
       print_atags(atags);
 
       puts("__ end of ATAGS contents __");
+
+      memory_size = find_memory_size(atags);
     }
 
+  if (memory_size)
+    {
+      char *unit;
+      uint32_t size_in_unit;
+
+      if (memory_size % POWER_OF_2(10))
+	{
+	  unit = "B";
+	  size_in_unit = memory_size;
+	}
+      else if (memory_size % POWER_OF_2(20))
+	{
+	  unit = "KB";
+	  size_in_unit = memory_size / POWER_OF_2(10);
+	}
+      else if (memory_size % POWER_OF_2(30))
+	{
+	  unit = "MB";
+	  size_in_unit = memory_size / POWER_OF_2(20);
+	}
+      else
+	{
+	  unit = "GB";
+	  size_in_unit = memory_size / POWER_OF_2(30);
+	}
+      
+      prints("memory available: ");
+      printdect(size_in_unit); puts(unit);
+    }
+  else
+    {
+      // Most Pis have move, but qemu might give us little
+      puts("Couldn't determine available memory - assuming 192MB");
+      memory_size = 192 * POWER_OF_2(20);
+    }
+  
   // prints some info
   demo_paging_support();