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'
Signed-off-by: Graeme Russ graeme.russ@gmail.com --- arch/i386/cpu/start.S | 6 ++++++ arch/i386/include/asm/global_data.h | 28 +++++++++++++++------------- arch/i386/lib/board.c | 25 ++++++++++++++----------- 3 files changed, 35 insertions(+), 24 deletions(-)
diff --git a/arch/i386/cpu/start.S b/arch/i386/cpu/start.S index 0f13399..6554f58 100644 --- a/arch/i386/cpu/start.S +++ b/arch/i386/cpu/start.S @@ -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! */
diff --git a/arch/i386/include/asm/global_data.h b/arch/i386/include/asm/global_data.h index a15c598..5971123 100644 --- a/arch/i386/include/asm/global_data.h +++ b/arch/i386/include/asm/global_data.h @@ -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 diff --git a/arch/i386/lib/board.c b/arch/i386/lib/board.c index 9c2f77f..1129918 100644 --- a/arch/i386/lib/board.c +++ b/arch/i386/lib/board.c @@ -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(); - - /* First stage Board initialization */ - if (board_early_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(); + }
/* 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)