On Sat, Nov 1, 2008 at 6:32 PM, Carl-Daniel Hailfinger < c-d.hailfinger.devel.2006@gmx.net> wrote:
On 01.11.2008 23:21, Carl-Daniel Hailfinger wrote:
Once we touch the MTRRs in VIA disable_car(), the CPU resets. Since workarounds are better than instant reboots, mangle the code so that it only switches stacks and flushes the cache.
There are two genuine fixes in there as well: Switch %esp before CAR is disabled. That way, debugging becomes easier and the stack is always
valid.
And one of the nastier bugs easily happening in C: We had a pointer to a const struct, but we wanted a const pointer to a struct. This kills the (correct) warning about that code.
Many thanks to Corey for testing countless iterations of that code.
Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net
Attached for poor gmail users.
New version attached. It also fixes a missing semicolon that somehow snuck into the earlier patch.
Index: corebootv3-via_car/arch/x86/via/stage1.c
=================================================================== --- corebootv3-via_car/arch/x86/via/stage1.c (Revision 977) +++ corebootv3-via_car/arch/x86/via/stage1.c (Arbeitskopie) @@ -35,6 +35,7 @@ */ void disable_car(void) {
- printk(BIOS_DEBUG, "disable_car entry\n"); /* Determine new global variable location. Stack organization from top
- Top 4 bytes are reserved
- Pointer to global variables
@@ -42,19 +43,28 @@ * * Align the result to 8 bytes */
- const struct global_vars *newlocation = (struct global_vars
*)((RAM_STACK_BASE - sizeof(struct global_vars *) - sizeof(struct global_vars)) & ~0x7);
- struct global_vars *const newlocation = (struct global_vars
*)((RAM_STACK_BASE - sizeof(struct global_vars *) - sizeof(struct global_vars)) & ~0x7); /* Copy global variables to new location. */ memcpy(newlocation, global_vars(), sizeof(struct global_vars));
- printk(BIOS_DEBUG, "disable_car global_vars copy done\n"); /* Set the new global variable pointer. */ *(struct global_vars **)(RAM_STACK_BASE - sizeof(struct global_vars
*)) = newlocation;
- printk(BIOS_DEBUG, "disable_car global_vars pointer adjusted\n");
- printk(BIOS_DEBUG, "entering asm code now\n");
+#define HALT_AFTER 2
I don't think we need that anymore ;) Tested and Acked-by: Corey Osgood corey.osgood@gmail.com