Initial Program Loader (IPL) usually runs with .text and .rodata
in ROM, while .data and .bss reside in RAM.
This patch uses the AT keyword to specify load address,
and a small code snippet in crt0.S to restore .data section
at runtime.
Example usage:
Assume the target device has a 4KB ROM at 0x00000000 and a
4KB SRAM at 0xA0000000, the IPL/SPL config could be:
#define CONFIG_SPL_MAX_SIZE 0x1000 /* text + data, no bss */
#define CONFIG_SPL_TEXT_BASE 0x00000000
#define CONFIG_SPL_DATA_BASE 0xA0000000
#define CONFIG_SPL_STACK 0xA0001000
Signed-off-by: Kuo-Jung Su <dant...@gmail.com>
Cc: Albert Aribaud <albert.u.b...@aribaud.net>
---
README | 10 ++++++++++
arch/arm/cpu/u-boot-spl.lds | 26 ++++++++++++++++++++++++--
arch/arm/lib/crt0.S | 22 ++++++++++++++++++++++
spl/Makefile | 6 ++++++
4 files changed, 62 insertions(+), 2 deletions(-)
diff --git a/README b/README
index a8d3039..992064a 100644
--- a/README
+++ b/README
@@ -3094,6 +3094,16 @@ FIT uImage format:
Address to relocate to. If unspecified, this is equal to
CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
+ CONFIG_SPL_DATA_BASE
+ Link address for the .data and .bss within the SPL binary.
+ CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_DATA_BASE
+ must not be both defined at the same time.
+
+ CONFIG_SPL_DATA_MAX_SIZE
+ Maximum size in memory allocated to the SPL .data + .bss.
+ When defined, the linker checks that the actual memory used
+ by SPL from __data_start to __bss_end does not exceed it.
+
CONFIG_SPL_BSS_START_ADDR
Link address for the BSS within the SPL binary.
diff --git a/arch/arm/cpu/u-boot-spl.lds b/arch/arm/cpu/u-boot-spl.lds
index 36cc54a..ea6284f 100644
--- a/arch/arm/cpu/u-boot-spl.lds
+++ b/arch/arm/cpu/u-boot-spl.lds
@@ -26,15 +26,28 @@ SECTIONS
.rodata : { *(SORT_BY_ALIGNMENT(SORT_BY_NAME(.rodata*))) }
. = ALIGN(4);
- .data : {
+
+#if defined(CONFIG_SPL_DATA_BASE)
+ __image_copy_end = .;
+
+ .data : AT ( __image_copy_end )
+#else
+ .data :
+#endif
+ {
+ __data_start = .;
*(.data*)
+ . = ALIGN(4);
+ __data_end = .;
}
. = ALIGN(4);
. = .;
+#if !defined(CONFIG_SPL_DATA_BASE)
__image_copy_end = .;
+#endif
.rel.dyn : {
__rel_dyn_start = .;
@@ -59,11 +72,20 @@ SECTIONS
/DISCARD/ : { *(.gnu*) }
}
-#if defined(CONFIG_SPL_MAX_SIZE)
+#if defined(CONFIG_SPL_MAX_SIZE) && defined(CONFIG_SPL_DATA_BASE)
+ASSERT((__image_copy_end - __image_copy_start) + \
+ (__data_end - __data_start) < (CONFIG_SPL_MAX_SIZE), \
+ "SPL image too big");
+#elif defined(CONFIG_SPL_MAX_SIZE)
ASSERT(__image_copy_end - __image_copy_start < (CONFIG_SPL_MAX_SIZE), \
"SPL image too big");
#endif
+#if defined(CONFIG_SPL_DATA_MAX_SIZE)
+ASSERT(__bss_end - __data_start < (CONFIG_SPL_DATA_MAX_SIZE), \
+ "SPL image DATA plus BSS too big");
+#endif
+
#if defined(CONFIG_SPL_BSS_MAX_SIZE)
ASSERT(__bss_end - __bss_start < (CONFIG_SPL_BSS_MAX_SIZE), \
"SPL image BSS too big");
diff --git a/arch/arm/lib/crt0.S b/arch/arm/lib/crt0.S
index ac54b93..46d0e03 100644
--- a/arch/arm/lib/crt0.S
+++ b/arch/arm/lib/crt0.S
@@ -58,6 +58,28 @@
ENTRY(_main)
/*
+ * Restore .data (initialized) section
+ */
+
+#if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_DATA_BASE)
+
+ /* Load values from the board-specific linker script. */
+ ldr r0, =__image_copy_end /* source start address */
+ ldr r1, =__data_start
+ ldr r2, =__data_end
+ sub r2, r2, r1
+ add r2, r0, r2 /* source end address */
+ ldr r1, =CONFIG_SPL_DATA_BASE
+
+data_copy:
+ ldmia r0!, {r3-r10} /* copy from source address [r0] */
+ stmia r1!, {r3-r10} /* copy to target address [r1] */
+ cmp r0, r2 /* until source end addreee [r2] */
+ blo data_copy
+
+#endif /* CONFIG_SPL_BUILD && CONFIG_SPL_DATA_BASE */
+
+/*
* Set up initial C runtime environment and call board_init_f(0).
*/
diff --git a/spl/Makefile b/spl/Makefile
index 29d7818..540ef8c 100644
--- a/spl/Makefile
+++ b/spl/Makefile
@@ -54,6 +54,12 @@ ifeq ($(CPU),mpc85xx)
START += $(START_PATH)/resetvec.o
endif
+ifdef CONFIG_SPL_DATA_BASE
+LDFLAGS += -Ttext $(CONFIG_SPL_TEXT_BASE) -Tdata $(CONFIG_SPL_DATA_BASE)
+else
+LDFLAGS += -Ttext $(CONFIG_SPL_TEXT_BASE)
+endif
+
LIBS-y += arch/$(ARCH)/lib/
LIBS-y += $(CPUDIR)/
--
1.7.9.5
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