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authorGraeme Russ <graeme.russ@gmail.com>2010-10-07 20:03:29 +1100
committerGraeme Russ <graeme.russ@gmail.com>2010-10-07 20:03:29 +1100
commit161b3589ea19ad262a2eebbf7b4f10aeb6812f35 (patch)
tree0f25a9a4ded4cb28b5ee819f0fa403ee5bd95712 /arch/i386
parent5a3876d2ac0aaaf16d50ce91b03c2030822da66f (diff)
downloadu-boot-linaro-stable-161b3589ea19ad262a2eebbf7b4f10aeb6812f35.tar.gz
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
Diffstat (limited to 'arch/i386')
-rw-r--r--arch/i386/cpu/start.S8
-rw-r--r--arch/i386/include/asm/global_data.h24
-rw-r--r--arch/i386/lib/board.c42
3 files changed, 37 insertions, 37 deletions
diff --git a/arch/i386/cpu/start.S b/arch/i386/cpu/start.S
index 66ff4f3e0..cff463758 100644
--- a/arch/i386/cpu/start.S
+++ b/arch/i386/cpu/start.S
@@ -25,6 +25,7 @@
#include <config.h>
#include <version.h>
+#include <asm/global_data.h>
.section .text
@@ -127,6 +128,13 @@ mem_ok:
/* Set the upper memory limit parameter */
subl $CONFIG_SYS_STACK_SIZE, %eax
+ /* Reserve space for global data */
+ subl $(GD_SIZE * 4), %eax
+
+ /* %eax points to the global data structure */
+ movl %esp, (GD_RAM_SIZE * 4)(%eax)
+ movl %ebx, (GD_FLAGS * 4)(%eax)
+
call board_init_f /* Enter, U-boot! */
/* indicate (lack of) progress */
diff --git a/arch/i386/include/asm/global_data.h b/arch/i386/include/asm/global_data.h
index 3a9adc9c6..456f606ec 100644
--- a/arch/i386/include/asm/global_data.h
+++ b/arch/i386/include/asm/global_data.h
@@ -33,6 +33,8 @@
* Keep it *SMALL* and remember to set CONFIG_SYS_GBL_DATA_SIZE > sizeof(gd_t)
*/
+#ifndef __ASSEMBLY__
+
typedef struct {
bd_t *bd;
unsigned long flags;
@@ -49,6 +51,26 @@ typedef struct {
char env_buf[32]; /* buffer for getenv() before reloc. */
} gd_t;
+extern gd_t *gd;
+
+#endif
+
+/* Word Offsets into Global Data - MUST match struct gd_t */
+#define GD_BD 0
+#define GD_FLAGS 1
+#define GD_BAUDRATE 2
+#define GD_HAVE_CONSOLE 3
+#define GD_RELOC_OFF 4
+#define GD_ENV_ADDR 5
+#define GD_ENV_VALID 6
+#define GD_CPU_CLK 7
+#define GD_BUS_CLK 8
+#define GD_RAM_SIZE 9
+#define GD_RESET_STATUS 10
+#define GD_JT 11
+
+#define GD_SIZE 12
+
/*
* Global Data Flags
*/
@@ -61,8 +83,6 @@ typedef struct {
#define GD_FLG_DISABLE_CONSOLE 0x00040 /* Disable console (in & out) */
#define GD_FLG_ENV_READY 0x00080 /* Environment imported into hash table */
-extern gd_t *gd;
-
#define DECLARE_GLOBAL_DATA_PTR
#endif /* __ASM_GBL_DATA_H */
diff --git a/arch/i386/lib/board.c b/arch/i386/lib/board.c
index 5002203ec..00976a5d4 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;