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Re: small custom bootloader to start an app stored in flash
- From: Oleg Uzenkov <o dot uzenkov at unicore dot co dot ua>
- To: Edgar Grimberg <edgar dot grimberg at gmail dot com>
- Cc: eCos Discussion <ecos-discuss at sourceware dot org>
- Date: Wed, 22 Oct 2014 14:08:33 +0300
- Subject: Re: small custom bootloader to start an app stored in flash
- Authentication-results: sourceware.org; auth=none
- References: <544618E5 dot 90101 at unicore dot co dot ua> <CAPrjMDAi=cqTSQ-d-c9FF53W-c6=v0j8rzSLQfuTcBQUY43Zpw at mail dot gmail dot com>
Thanks,
Any ideas how to make a jump to start an app? May be some sample code
showing how to do it in eCos? May be someone has done it already?
// Make a function pointer and assigned it to the address you want to jump to.
void (*startApp1)(void) = 0x08002000 ;
// Disable the interrupts.
cyg_interrupt_disable();
//Call the function.
startApp1();
I have tried it but could not get it working yet (stm32f4-discovery board).
May be I am missing something in the understanding of the principles.
Please could you check.
1. Here is the code of my bootloader:
...
static void (*startApp)(void) = ( void(*)(void) ) (0x08020000) ;
int main (void) {
diag_printf( "IN JUMP\n" );
cyg_interrupt_disable();
startApp();
while (1);
return 0;
}
I build it with ROM startup and flash at 0x08000000
mlt files:
*.ldi:
MEMORY
{
ram : ORIGIN = 0x20000000, LENGTH =
0x00020000-CYGNUM_HAL_COMMON_INTERRUPTS_STACK_SIZE
flash : ORIGIN = 0x08000000, LENGTH = 0x00100000
ccm : ORIGIN = 0x10000000, LENGTH = 0x00010000
}
hal_vsr_table = 0x20000000;
hal_virtual_vector_table = hal_vsr_table + 98*4;
#if defined(CYGSEM_HAL_VIRTUAL_VECTOR_SUPPORT)
hal_virtual_vector_table_end = hal_virtual_vector_table + 64*4;
#else // zero size virtual vector table
hal_virtual_vector_table_end = hal_virtual_vector_table;
#endif
// SRAM is 128k.
hal_startup_stack = 0x20000000 + 1024*128;
SECTIONS
{
SECTIONS_BEGIN
USER_SECTION (ccm, ccm, 0x10000000 (NOLOAD), LMA_EQ_VMA)
SECTION_rom_vectors (flash, 0x08000000, LMA_EQ_VMA)
SECTION_RELOCS (flash, ALIGN (0x8), LMA_EQ_VMA)
SECTION_text (flash, ALIGN (0x8), LMA_EQ_VMA)
SECTION_fini (flash, ALIGN (0x8), LMA_EQ_VMA)
SECTION_rodata (flash, ALIGN (0x8), LMA_EQ_VMA)
SECTION_rodata1 (flash, ALIGN (0x8), LMA_EQ_VMA)
SECTION_fixup (flash, ALIGN (0x8), LMA_EQ_VMA)
SECTION_gcc_except_table (flash, ALIGN (0x8), LMA_EQ_VMA)
SECTION_eh_frame (flash, ALIGN (0x8), LMA_EQ_VMA)
SECTION_got (flash, ALIGN (0x8), LMA_EQ_VMA)
SECTION_sram (ram, hal_virtual_vector_table_end, FOLLOWING (.got))
SECTION_data (ram, ALIGN( 0x8), FOLLOWING (.sram))
SECTION_bss (ram, ALIGN (0x8), LMA_EQ_VMA)
CYG_LABEL_DEFN(__heap1) = ALIGN (0x8);
SECTIONS_END
}
*.h:
#define CYGMEM_REGION_ram (0x20000000)
#define CYGMEM_REGION_ram_SIZE
(0x00020000-CYGNUM_HAL_COMMON_INTERRUPTS_STACK_SIZE)
#define CYGMEM_REGION_ram_ATTR (CYGMEM_REGION_ATTR_R | CYGMEM_REGION_ATTR_W)
#define CYGMEM_REGION_ccm (0x10000000)
#define CYGMEM_REGION_ccm_SIZE (0x00010000)
#define CYGMEM_REGION_ccm_ATTR (CYGMEM_REGION_ATTR_R | CYGMEM_REGION_ATTR_W)
#define CYGMEM_REGION_flash (0x08000000)
#define CYGMEM_REGION_flash_SIZE (0x00100000)
#define CYGMEM_REGION_flash_ATTR (CYGMEM_REGION_ATTR_R |
CYGMEM_REGION_ATTR_W)
#ifndef __ASSEMBLER__
extern char CYG_LABEL_NAME (__heap1) [];
#endif
#define CYGMEM_SECTION_heap1 (CYG_LABEL_NAME (__heap1))
#define CYGMEM_SECTION_heap1_SIZE
(CYGMEM_REGION_ram+CYGMEM_REGION_ram_SIZE - (size_t) CYG_LABEL_NAME
(__heap1))
2. Here is the code of my app to which I want to jump to:
int main (void) {
diag_printf( "IN APP\n" );
while (1);
return 0;
}
I build it with ROM startup and flash it at 0x08020000
mlt files:
*.ldi:
MEMORY
{
ram : ORIGIN = 0x20000000, LENGTH =
0x00020000-CYGNUM_HAL_COMMON_INTERRUPTS_STACK_SIZE
flash : ORIGIN = 0x08020000, LENGTH = 0x00100000 - 0x20000
ccm : ORIGIN = 0x10000000, LENGTH = 0x00010000
}
hal_vsr_table = 0x20000000;
hal_virtual_vector_table = hal_vsr_table + 98*4;
#if defined(CYGSEM_HAL_VIRTUAL_VECTOR_SUPPORT)
hal_virtual_vector_table_end = hal_virtual_vector_table + 64*4;
#else // zero size virtual vector table
hal_virtual_vector_table_end = hal_virtual_vector_table;
#endif
// SRAM is 128k.
hal_startup_stack = 0x20000000 + 1024*128;
SECTIONS
{
SECTIONS_BEGIN
USER_SECTION (ccm, ccm, 0x10000000 (NOLOAD), LMA_EQ_VMA)
SECTION_rom_vectors (flash, 0x08020000, LMA_EQ_VMA)
SECTION_RELOCS (flash, ALIGN (0x8), LMA_EQ_VMA)
SECTION_text (flash, ALIGN (0x8), LMA_EQ_VMA)
SECTION_fini (flash, ALIGN (0x8), LMA_EQ_VMA)
SECTION_rodata (flash, ALIGN (0x8), LMA_EQ_VMA)
SECTION_rodata1 (flash, ALIGN (0x8), LMA_EQ_VMA)
SECTION_fixup (flash, ALIGN (0x8), LMA_EQ_VMA)
SECTION_gcc_except_table (flash, ALIGN (0x8), LMA_EQ_VMA)
SECTION_eh_frame (flash, ALIGN (0x8), LMA_EQ_VMA)
SECTION_got (flash, ALIGN (0x8), LMA_EQ_VMA)
SECTION_sram (ram, hal_virtual_vector_table_end, FOLLOWING (.got))
SECTION_data (ram, ALIGN( 0x8), FOLLOWING (.sram))
SECTION_bss (ram, ALIGN (0x8), LMA_EQ_VMA)
CYG_LABEL_DEFN(__heap1) = ALIGN (0x8);
SECTIONS_END
}
*.h:
#define CYGMEM_REGION_ram (0x20000000)
#define CYGMEM_REGION_ram_SIZE
(0x00020000-CYGNUM_HAL_COMMON_INTERRUPTS_STACK_SIZE)
#define CYGMEM_REGION_ram_ATTR (CYGMEM_REGION_ATTR_R | CYGMEM_REGION_ATTR_W)
#define CYGMEM_REGION_ccm (0x10000000)
#define CYGMEM_REGION_ccm_SIZE (0x00010000)
#define CYGMEM_REGION_ccm_ATTR (CYGMEM_REGION_ATTR_R | CYGMEM_REGION_ATTR_W)
#define CYGMEM_REGION_flash (0x08020000)
#define CYGMEM_REGION_flash_SIZE (0x00100000 - 0x20000)
#define CYGMEM_REGION_flash_ATTR (CYGMEM_REGION_ATTR_R |
CYGMEM_REGION_ATTR_W)
#ifndef __ASSEMBLER__
extern char CYG_LABEL_NAME (__heap1) [];
#endif
#define CYGMEM_SECTION_heap1 (CYG_LABEL_NAME (__heap1))
#define CYGMEM_SECTION_heap1_SIZE
(CYGMEM_REGION_ram+CYGMEM_REGION_ram_SIZE - (size_t) CYG_LABEL_NAME
(__heap1))
3. I am expecting output to be:
IN JUMP
IN APP
But I do not get to IN APP.
What am I doing wrong?
I tried to jump to 0x08020004 address as it is where hal_reset_vsr is,
but still no luck.
ROM startup build copies .data and .bss sections into ram, probably
these sections data gets overwritten.
Do I need to shift addresses of SECTION_sram, SECTION_data, SECTION_bss
in app's memory layout?
Oleg
P.S:
$ arm-none-eabi-readelf -h app.elf
ELF Header:
Magic: 7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00
Class: ELF32
Data: 2's complement, little endian
Version: 1 (current)
OS/ABI: UNIX - System V
ABI Version: 0
Type: EXEC (Executable file)
Machine: ARM
Version: 0x1
Entry point address: 0x8020111
Start of program headers: 52 (bytes into file)
Start of section headers: 24148 (bytes into file)
Flags: 0x5000002, has entry point,
Version5 EABI
Size of this header: 52 (bytes)
Size of program headers: 32 (bytes)
Number of program headers: 3
Size of section headers: 40 (bytes)
Number of section headers: 12
Section header string table index: 11
$ arm-none-eabi-objdump -h app.elf
app.elf: file format elf32-littlearm
Sections:
Idx Name Size VMA LMA File off Algn
0 .rom_vectors 00000008 08020000 08020000 00000098 2**0
CONTENTS, ALLOC, LOAD, READONLY, CODE
1 .ARM.extab 0000003c 08020008 08020008 000000a0 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
2 .ARM.exidx 000000c8 08020048 08020048 000000e0 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
3 .text 0000586c 08020110 08020110 000001a8 2**3
CONTENTS, ALLOC, LOAD, READONLY, CODE
4 .rodata 0000010d 08025980 08025980 00005a18 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
5 .eh_frame 00000008 08025a90 08025a90 00005b25 2**0
ALLOC
6 .data 00000268 20000288 08025a98 00005b28 2**3
CONTENTS, ALLOC, LOAD, DATA
7 .bss 000034e8 200004f0 08025d00 00005d90 2**3
ALLOC
8 .ARM.attributes 0000002d 00000000 00000000 00005d90 2**0
CONTENTS, READONLY
9 .comment 0000002a 00000000 00000000 00005dbd 2**0
CONTENTS, READONLY
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