In order to locate the 16-bit BIOS code, we need to know the reloaction offset.
--- This was a lot tricker than it should have been --- lib_i386/board.c | 63 ++++++++++++++++++++++++++++++----------------------- 1 files changed, 36 insertions(+), 27 deletions(-)
diff --git a/lib_i386/board.c b/lib_i386/board.c index 5e28c6f..947a8ec 100644 --- a/lib_i386/board.c +++ b/lib_i386/board.c @@ -52,7 +52,9 @@ extern ulong _i386boot_rel_dyn_start; extern ulong _i386boot_rel_dyn_end; extern ulong _i386boot_bss_start; extern ulong _i386boot_bss_size; -void ram_bootstrap (void *); + +void ram_bootstrap (void *, ulong); + const char version_string[] = U_BOOT_VERSION" (" U_BOOT_DATE " - " U_BOOT_TIME ")";
@@ -162,6 +164,7 @@ init_fnc_t *init_sequence[] = { NULL, };
+static gd_t gd_data; gd_t *gd;
/* @@ -174,21 +177,18 @@ void board_init_f (ulong stack_limit) Elf32_Rel *rel_dyn_start = (Elf32_Rel *)&_i386boot_rel_dyn_start; Elf32_Rel *rel_dyn_end = (Elf32_Rel *)&_i386boot_rel_dyn_end; void *bss_start = &_i386boot_bss_start; - void *bss_size = &_i386boot_bss_size; + ulong bss_size = (ulong)&_i386boot_bss_size;
- size_t uboot_size; - void *ram_start; + ulong uboot_size; + void *dest_addr; ulong rel_offset; Elf32_Rel *re;
- void (*start_func)(void *); - - /* compiler optimization barrier needed for GCC >= 3.4 */ - __asm__ __volatile__("": : :"memory"); + void (*start_func)(void *, ulong);
- uboot_size = (size_t)u_boot_cmd_end - (size_t)text_start; - ram_start = (void *)stack_limit - (uboot_size + (ulong)bss_size); - rel_offset = text_start - ram_start; + uboot_size = (ulong)u_boot_cmd_end - (ulong)text_start; + dest_addr = (void *)stack_limit - (uboot_size + (ulong)bss_size); + rel_offset = text_start - dest_addr; start_func = ram_bootstrap - rel_offset;
/* First stage CPU initialization */ @@ -200,10 +200,10 @@ void board_init_f (ulong stack_limit) hang();
/* Copy U-Boot into RAM */ - memcpy(ram_start, text_start, (size_t)uboot_size); + memcpy(dest_addr, text_start, uboot_size);
/* Clear BSS */ - memset(bss_start - rel_offset, 0, (size_t)bss_size); + memset(bss_start - rel_offset, 0, bss_size);
/* Perform relocation adjustments */ for (re = rel_dyn_start; re < rel_dyn_end; re++) @@ -213,27 +213,39 @@ void board_init_f (ulong stack_limit) *(ulong *)(re->r_offset - rel_offset) -= (Elf32_Addr)rel_offset; }
- start_func(ram_start); - - /* NOTREACHED - relocate_code() does not return */ + /* Enter the relocated U-Boot! */ + start_func(dest_addr, rel_offset); + /* NOTREACHED - board_init_f() does not return */ while(1); }
/* - * All attempts to jump straight from board_init_f() to board_init_r() - * have failed, hence this special 'bootstrap' function. + * 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 *ram_start) +void ram_bootstrap (void *dest_addr, ulong rel_offset) { - static gd_t gd_data; - /* compiler optimization barrier needed for GCC >= 3.4 */ __asm__ __volatile__("": : :"memory");
- board_init_r(&gd_data, (ulong)ram_start); + /* 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 ram_start) +void board_init_r(gd_t *id, ulong dest_addr) { char *s; int i; @@ -247,16 +259,13 @@ void board_init_r(gd_t *id, ulong ram_start) /* compiler optimization barrier needed for GCC >= 3.4 */ __asm__ __volatile__("": : :"memory");
- memset (gd, 0, sizeof (gd_t)); gd->bd = &bd_data; memset (gd->bd, 0, sizeof (bd_t)); show_boot_progress(0x22);
gd->baudrate = CONFIG_BAUDRATE;
- gd->flags |= GD_FLG_RELOC; /* tell others: relocation done */ - - mem_malloc_init((((ulong)ram_start - CONFIG_SYS_MALLOC_LEN)+3)&~3, + mem_malloc_init((((ulong)dest_addr - CONFIG_SYS_MALLOC_LEN)+3)&~3, CONFIG_SYS_MALLOC_LEN);
for (init_fnc_ptr = init_sequence, i=0; *init_fnc_ptr; ++init_fnc_ptr, i++) {