From 161b3589ea19ad262a2eebbf7b4f10aeb6812f35 Mon Sep 17 00:00:00 2001 From: Graeme Russ Date: Thu, 7 Oct 2010 20:03:29 +1100 Subject: 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 --- arch/i386/lib/board.c | 42 +++++++----------------------------------- 1 file changed, 7 insertions(+), 35 deletions(-) (limited to 'arch/i386/lib/board.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_rel_dyn_end; 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 @@ init_fnc_t *init_sequence[] = { 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 @@ void board_init_f (ulong stack_limit) 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 @@ void board_init_f (ulong stack_limit) *(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; -- cgit v1.1