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x86: Implement fully relocatable image

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u-boot.bin can be loaded at any 4-byte aligned memory location and directly
'jumped' to using the 'go' command using the load address as the start
address. Doing so performs a 'warm boot' which skips memory initialisation
and other low-level initialisations, relocates U-Boot to upper memory and
starts U-Boot in RAM as per normal 'cold boot'
This commit is contained in:
Graeme Russ 2010-10-07 20:03:33 +11:00
parent f2ff75c0a2
commit c868af3e57
3 changed files with 34 additions and 23 deletions
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6
arch/i386/cpu/start.S
View file

@ -118,6 +118,11 @@ mem_ok:
wbinvd
/* Determine our load offset */
call 1f
1: popl %ecx
subl $1b, %ecx
/* Set the upper memory limit parameter */
subl $CONFIG_SYS_STACK_SIZE, %eax
@ -127,6 +132,7 @@ mem_ok:
/* %eax points to the global data structure */
movl %esp, (GD_RAM_SIZE * 4)(%eax)
movl %ebx, (GD_FLAGS * 4)(%eax)
movl %ecx, (GD_LOAD_OFF * 4)(%eax)
call board_init_f /* Enter, U-boot! */

28
arch/i386/include/asm/global_data.h
View file

@ -41,6 +41,7 @@ typedef struct {
unsigned long baudrate;
unsigned long have_console; /* serial_init() was called */
unsigned long reloc_off; /* Relocation Offset */
unsigned long load_off; /* Load Offset */
unsigned long env_addr; /* Address of Environment struct */
unsigned long env_valid; /* Checksum of Environment valid? */
unsigned long cpu_clk; /* CPU clock in Hz! */
@ -56,20 +57,21 @@ 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_BD 0
#define GD_FLAGS 1
#define GD_BAUDRATE 2
#define GD_HAVE_CONSOLE 3
#define GD_RELOC_OFF 4
#define GD_LOAD_OFF 5
#define GD_ENV_ADDR 6
#define GD_ENV_VALID 7
#define GD_CPU_CLK 8
#define GD_BUS_CLK 9
#define GD_RAM_SIZE 10
#define GD_RESET_STATUS 11
#define GD_JT 12
#define GD_SIZE 12
#define GD_SIZE 13
/*
* Global Data Flags

23
arch/i386/lib/board.c
View file

@ -190,18 +190,21 @@ void board_init_f (ulong gdp)
dest_addr = (void *)gdp - (bss_end - text_start);
rel_offset = text_start - dest_addr;
/* First stage CPU initialization */
if (cpu_init_f() != 0)
hang();
/* Perform low-level initialization only when cold booted */
if (((gd_t *)gdp)->flags & GD_FLG_COLD_BOOT) {
/* First stage CPU initialization */
if (cpu_init_f() != 0)
hang();
/* First stage Board initialization */
if (board_early_init_f() != 0)
hang();
/* First stage Board initialization */
if (board_early_init_f() != 0)
hang();
}
/* Copy U-Boot into RAM */
dst_addr = (ulong *)dest_addr;
src_addr = (ulong *)text_start;
end_addr = (ulong *)data_end;
src_addr = (ulong *)(text_start + ((gd_t *)gdp)->load_off);
end_addr = (ulong *)(data_end + ((gd_t *)gdp)->load_off);
while (src_addr < end_addr)
*dst_addr++ = *src_addr++;
@ -214,8 +217,8 @@ void board_init_f (ulong gdp)
*dst_addr++ = 0x00000000;
/* Perform relocation adjustments */
re_src = (Elf32_Rel *)rel_dyn_start;
re_end = (Elf32_Rel *)rel_dyn_end;
re_src = (Elf32_Rel *)(rel_dyn_start + ((gd_t *)gdp)->load_off);
re_end = (Elf32_Rel *)(rel_dyn_end + ((gd_t *)gdp)->load_off);
do {
if (re_src->r_offset >= TEXT_BASE)