New version which takes into account everything mentioned in the discussion.
We need a way to find out where our stack and our global variables are
at any given moment. The code is generic enough to handle this in a
processor-specific way behind the scenes if needed.
Signed-off-by: Carl-Daniel Hailfinger <[EMAIL PROTECTED]>
Index: corebootv3-globalvariablelocation/include/arch/x86/cpu.h
===================================================================
--- corebootv3-globalvariablelocation/include/arch/x86/cpu.h (Revision 931)
+++ corebootv3-globalvariablelocation/include/arch/x86/cpu.h (Arbeitskopie)
@@ -266,11 +266,17 @@
struct global_vars * global_vars(void);
EXPORT_SYMBOL(global_vars);
+#define CAR_STACK_BASE (CONFIG_CARBASE + CONFIG_CARSIZE - 4)
+#define RAM_STACK_BASE 0x88ffc
+
#ifdef CONFIG_CONSOLE_BUFFER
#define PRINTK_BUF_SIZE_CAR (CONFIG_CARSIZE / 2)
#define PRINTK_BUF_ADDR_CAR CONFIG_CARBASE
#define PRINTK_BUF_SIZE_RAM 65536
#define PRINTK_BUF_ADDR_RAM 0x90000
+#define CAR_STACK_SIZE ((CONFIG_CARSIZE / 2) - 4)
+#else
+#define CAR_STACK_SIZE (CONFIG_CARSIZE - 4)
#endif
/* resource maps. These started out as special for the K8 but now have more
general usage */
Index: corebootv3-globalvariablelocation/arch/x86/stage1.c
===================================================================
--- corebootv3-globalvariablelocation/arch/x86/stage1.c (Revision 931)
+++ corebootv3-globalvariablelocation/arch/x86/stage1.c (Arbeitskopie)
@@ -70,11 +70,21 @@
/*
* The name is slightly misleading because this is the initial stack pointer,
* not the address of the first element on the stack.
+ * NOTE: This function is very processor specific.
*/
void *bottom_of_stack(void)
{
- /* -4 because CONFIG_CARBASE + CONFIG_CARSIZE - 4 is initial %esp */
- return (void *)(CONFIG_CARBASE + CONFIG_CARSIZE - 4);
+ u32 onstack = (u32)&onstack;
+
+ /* Check whether the variable onstack is inside the CAR stack area.
+ * If it is, assume we're still in CAR or the stack has not moved.
+ * Otherwise return initial %esp for the RAM-based stack location.
+ */
+ if ((onstack >= CAR_STACK_BASE - CAR_STACK_SIZE) &&
+ (onstack < CAR_STACK_BASE))
+ return (void *)CAR_STACK_BASE;
+ /* OK, so current %esp is not inside the CAR stack area. */
+ return (void *)RAM_STACK_BASE;
}
struct global_vars *global_vars(void)
--
http://www.hailfinger.org/
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