[coreboot] [RFC] v3: keep global variables in BSP stack only

[Carl-Daniel Hailfinger]

Currently v3 allocates a global variable struct on the stack for each
processor in stage1_main(). We only have 1k AP stack size for Fam10, but
struct global_vars is ~3.6k, so all AP stacks will smash each other. Bad.

The idea is to have a special stage1_main_bsp() which allocates struct
global_vars and initializes it.
The BSP calls stage1_main_bsp() from stage0, all APs call stage1_main().
stage1_main_bsp() will call stage1_main(), so all processors end up in
stage1_main() eventually.

The following snippet illustrates the changes to arch/x86/stage1.c and
the changes for an UP configuration of i586/stage0.S.

Index: arch/x86/i586/stage0.S
===================================================================
--- arch/x86/i586/stage0.S	(Revision 909)
+++ arch/x86/i586/stage0.S	(Arbeitskopie)
@@ -345,7 +345,7 @@
 	pushl	$0
 	/* First parameter: bist */
 	pushl	%eax
-	call	stage1_main
+	call	stage1_main_bsp
 	/* We will not go back. */
 
 fixed_mtrr_msr:
Index: arch/x86/stage1.c
===================================================================
--- arch/x86/stage1.c	(Revision 909)
+++ arch/x86/stage1.c	(Arbeitskopie)
@@ -143,6 +143,20 @@
 	return ret;
 }
 
+void __attribute__((stdcall)) stage1_main(u32 bist, u32 init_detected);
+
+void __attribute__((stdcall)) stage1_main_bsp(u32 bist, u32 init_detected)
+{
+	struct global_vars globvars;
+
+	/* Initialize global variables before we can think of using them.
+	 */
+	global_vars_init(&globvars);
+	globvars.init_detected = init_detected;
+	
+	stage1_main(bist, init_detected);
+}
+
 /**
  * This function is called from assembler code with its argument on the
  * stack. Force the compiler to generate always correct code for this case.
@@ -156,7 +170,6 @@
  */
 void __attribute__((stdcall)) stage1_main(u32 bist, u32 init_detected)
 {
-	struct global_vars globvars;
 	int ret;
 	struct mem_file archive;
 	void *entry;
@@ -185,11 +198,6 @@
 	 */
 	stop_ap();
 
-	/* Initialize global variables before we can think of using them.
-	 */
-	global_vars_init(&globvars);
-	globvars.init_detected = init_detected;
-
 	hardware_stage1();
 
 	//


-- 
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