x86: Place global data below stack before entering C
By reserving space for the Global Data immediately below the stack during
assembly level initialisation, the C declaration of the static global data
can be removed, along with the 'RAM Bootstrap' function. This results in
cleaner code, and the ability to pass boot-up flags from assembler into C
diff --git a/arch/i386/lib/board.c b/arch/i386/lib/board.c
index 5002203..00976a5 100644
--- a/arch/i386/lib/board.c
+++ b/arch/i386/lib/board.c
@@ -54,8 +54,6 @@
extern ulong _i386boot_bss_start;
extern ulong _i386boot_bss_size;
-void ram_bootstrap (void *, ulong);
-
const char version_string[] =
U_BOOT_VERSION" (" U_BOOT_DATE " - " U_BOOT_TIME ")";
@@ -164,13 +162,12 @@
NULL,
};
-static gd_t gd_data;
gd_t *gd;
/*
* Load U-Boot into RAM, initialize BSS, perform relocation adjustments
*/
-void board_init_f (ulong stack_limit)
+void board_init_f (ulong gdp)
{
void *text_start = &_i386boot_text_start;
void *u_boot_cmd_end = &__u_boot_cmd_end;
@@ -184,12 +181,9 @@
ulong rel_offset;
Elf32_Rel *re;
- void (*start_func)(void *, ulong);
-
uboot_size = (ulong)u_boot_cmd_end - (ulong)text_start;
- dest_addr = (void *)stack_limit - (uboot_size + (ulong)bss_size);
+ dest_addr = (void *)gdp - (uboot_size + (ulong)bss_size);
rel_offset = text_start - dest_addr;
- start_func = ram_bootstrap - rel_offset;
/* First stage CPU initialization */
if (cpu_init_f() != 0)
@@ -213,38 +207,16 @@
*(ulong *)(re->r_offset - rel_offset) -= (Elf32_Addr)rel_offset;
}
+ ((gd_t *)gdp)->reloc_off = rel_offset;
+ ((gd_t *)gdp)->flags |= GD_FLG_RELOC;
+
/* Enter the relocated U-Boot! */
- start_func(dest_addr, rel_offset);
+ (board_init_r - rel_offset)((gd_t *)gdp, (ulong)dest_addr);
+
/* NOTREACHED - board_init_f() does not return */
while(1);
}
-/*
- * We cannot initialize gd_data in board_init_f() because we would be
- * attempting to write to flash (I have even tried using manual relocation
- * adjustments on pointers but it just won't work) and board_init_r() does
- * not have enough arguments to allow us to pass the relocation offset
- * straight up. This bootstrap function (which runs in RAM) is used to
- * setup gd_data in order to pass the relocation offset to the rest of
- * U-Boot.
- *
- * TODO: The compiler optimization barrier is intended to stop GCC from
- * optimizing this function into board_init_f(). It seems to work without
- * it, but I've left it in to be sure. I think also that the barrier in
- * board_init_r() is no longer needed, but left it in 'just in case'
- */
-void ram_bootstrap (void *dest_addr, ulong rel_offset)
-{
- /* compiler optimization barrier needed for GCC >= 3.4 */
- __asm__ __volatile__("": : :"memory");
-
- /* tell others: relocation done */
- gd_data.reloc_off = rel_offset;
- gd_data.flags |= GD_FLG_RELOC;
-
- board_init_r(&gd_data, (ulong)dest_addr);
-}
-
void board_init_r(gd_t *id, ulong dest_addr)
{
char *s;
