Kernel/armv7 - Task switching now supported

[tpg/acess2.git] / Kernel / arch / armv7 / mm_virt.c

diff --git a/Kernel/arch/armv7/mm_virt.c b/Kernel/arch/armv7/mm_virt.c
index c191c68..0fc426d 100644 (file)
--- a/Kernel/arch/armv7/mm_virt.c
+++ b/Kernel/arch/armv7/mm_virt.c
@@ -324,9 +324,6 @@ void MM_SetFlags(tVAddr VAddr, Uint Flags, Uint Mask)
        tMM_PageInfo    pi;
        if( MM_int_GetPageInfo(VAddr, &pi) )
                return;
-       
-               
-
 }
 
 int MM_Map(tVAddr VAddr, tPAddr PAddr)
@@ -395,11 +392,46 @@ void MM_FreeTemp(tVAddr VAddr)
        // TODO: Implement FreeTemp
 }
 
-tVAddr MM_NewKStack(int bGlobal)
+tVAddr MM_NewKStack(int bShared)
 {
-       // TODO: Implement NewKStack
-       // TODO: Should I support global stacks? if only for the idle thread
-       return 0;
+       tVAddr  min_addr, max_addr;
+       tVAddr  addr, ofs;
+
+       if( bShared ) {
+               min_addr = MM_GLOBALSTACKS;
+               max_addr = MM_GLOBALSTACKS_END;
+       }
+       else {
+               min_addr = MM_KSTACK_BASE;
+               max_addr = MM_KSTACK_END;
+       }
+
+       // Locate a free slot
+       for( addr = min_addr; addr < max_addr; addr += MM_KSTACK_SIZE )
+       {
+               tMM_PageInfo    pi;
+               if( MM_int_GetPageInfo(addr+MM_KSTACK_SIZE-PAGE_SIZE, &pi) )    break;
+       }
+
+       // Check for an error   
+       if(addr >= max_addr) {
+               return 0;
+       }
+
+       // 1 guard page
+       for( ofs = PAGE_SIZE; ofs < MM_KSTACK_SIZE; ofs += PAGE_SIZE )
+       {
+               if( MM_Allocate(addr + ofs) == 0 ) {
+                       while(ofs)
+                       {
+                               ofs -= PAGE_SIZE;
+                               MM_Deallocate(addr + ofs);
+                       }
+                       Log_Warning("MMVirt", "MM_NewKStack: Unable to allocate");
+                       return 0;
+               }
+       }
+       return addr + ofs;
 }
 
 void MM_DumpTables(tVAddr Start, tVAddr End)