devel@lists.zephyrproject.org | Removing padding from generated hex files

Jamie Mccrae <Jamie.Mccrae@...>

#5885

Hi,

Is it possible when building projects to have the flash sections that are defined in the dts but unused (in this instance, the Nordic MBR) and not have them filled but instead left blank/empty? I have created a simple project and enabled mcuboot support in the build options, it uses the flash partition table correctly and places the code at 0x1000 instead of 0x0, but it has filled 0x0 – 0x1000 with 0x00 bytes, which if flashed will overwrite the Nordic MBR and leave a dead module. Instead, I would like to have code start at 0x1000, nothing at all placed between 0x0 – 0x1000, and the same in another section which is defined later, this is so that there can be external data present which isn’t overwritten when the application hex file is flashed to the module.

Thanks,

Jamie

Sebastian Boe

#5886

Hi,

try enabling

CONFIG_BUILD_NO_GAP_FILL

IMHO this should be the default. Needing to fill the gaps is indicative of a problem
elsewhere, e.g. in the linker scripts.

________________________________________
From: devel@lists.zephyrproject.org <devel@lists.zephyrproject.org> on behalf of  via Lists.Zephyrproject.Org <Jamie.Mccrae=lairdconnect.com@lists.zephyrproject.org>
Sent: Thursday, April 4, 2019 2:14 PM
To: devel@lists.zephyrproject.org
Cc: devel@lists.zephyrproject.org
Subject: [Zephyr-devel] Removing padding from generated hex files

Hi,
Is it possible when building projects to have the flash sections that are defined in the dts but unused (in this instance, the Nordic MBR) and not have them filled but instead left blank/empty? I have created a simple project and enabled mcuboot support in the build options, it uses the flash partition table correctly and places the code at 0x1000 instead of 0x0, but it has filled 0x0 – 0x1000 with 0x00 bytes, which if flashed will overwrite the Nordic MBR and leave a dead module. Instead, I would like to have code start at 0x1000, nothing at all placed between 0x0 – 0x1000, and the same in another section which is defined later, this is so that there can be external data present which isn’t overwritten when the application hex file is flashed to the module.
Thanks,
Jamie

lairdjm

#5887

Hi,
I have tried that but it still pads the first section with 0x00 bytes. I'm using a custom board file and project so tried switched to trying it with the hello world sample using the nrf52840_pca10059 board file and enabled the option there, the area where the MBR is, is filled with 0x00 inside the hex file.
Thanks,
Jamie

Show quoted text

-----Original Message-----

Hi,

try enabling

CONFIG_BUILD_NO_GAP_FILL

IMHO this should be the default. Needing to fill the gaps is indicative of a problem
elsewhere, e.g. in the linker scripts.

Sebastian Boe

#5888

Okay, if I was you I would have a look at the map file and try to figure out what it's putting there and why.

________________________________________
From: Jamie Mccrae <Jamie.Mccrae@lairdconnect.com>
Sent: Thursday, April 4, 2019 2:34 PM
To: Bøe, Sebastian; devel@lists.zephyrproject.org
Subject: RE: Removing padding from generated hex files

Hi,
I have tried that but it still pads the first section with 0x00 bytes. I'm using a custom board file and project so tried switched to trying it with the hello world sample using the nrf52840_pca10059 board file and enabled the option there, the area where the MBR is, is filled with 0x00 inside the hex file.
Thanks,
Jamie

-----Original Message-----

Hi,

try enabling

CONFIG_BUILD_NO_GAP_FILL

IMHO this should be the default. Needing to fill the gaps is indicative of a problem
elsewhere, e.g. in the linker scripts.

lairdjm

#5889

Hi,
That's where I'm not sure on, I see the fill section but can't work out where it's coming from:
	Memory Configuration

	Name             Origin             Length             Attributes
	FLASH            0x00000000         0x00100000         xr
	SRAM             0x20000000         0x00040000         xw
	IDT_LIST         0x20040000         0x00000800         xw
	*default*        0x00000000         0xffffffff

	Linker script and memory map

	LOAD zephyr/CMakeFiles/kernel_elf.dir/misc/empty_file.c.obj
	LOAD zephyr/CMakeFiles/kernel_elf.dir/isr_tables.c.obj
	LOAD app/libapp.a
	LOAD zephyr/libzephyr.a
	LOAD zephyr/arch/arch/arm/core/libarch__arm__core.a
	LOAD zephyr/arch/arch/arm/core/cortex_m/libarch__arm__core__cortex_m.a
	LOAD zephyr/arch/arch/arm/core/cortex_m/mpu/libarch__arm__core__cortex_m__mpu.a
	LOAD zephyr/lib/libc/minimal/liblib__libc__minimal.a
	LOAD zephyr/boards/arm/nrf52840_pca10059/libboards__arm__nrf52840_pca10059.a
	LOAD zephyr/drivers/serial/libdrivers__serial.a
	LOAD zephyr/kernel/libkernel.a
	LOAD zephyr/CMakeFiles/offsets.dir/arch/arm/core/offsets/offsets.c.obj
	LOAD c:/gcc-arm/bin/../lib/gcc/arm-none-eabi/8.2.1/thumb/v7e-m/nofp\libgcc.a
	                0x00000020                _region_min_align = 0x20

	.rel.plt        0x00000000        0x0
	 *(SORT_BY_ALIGNMENT(.rel.plt))
	                [!provide]                PROVIDE (__rel_iplt_start = .)
	 *(SORT_BY_ALIGNMENT(.rel.iplt))
	 .rel.iplt      0x00000000        0x0 zephyr/CMakeFiles/kernel_elf.dir/isr_tables.c.obj
	                [!provide]                PROVIDE (__rel_iplt_end = .)
	
	.rela.plt       0x00000000        0x0
	 *(SORT_BY_ALIGNMENT(.rela.plt))
	                [!provide]                PROVIDE (__rela_iplt_start = .)
	 *(SORT_BY_ALIGNMENT(.rela.iplt))
	                [!provide]                PROVIDE (__rela_iplt_end = .)

	.rel.dyn
	 *(SORT_BY_ALIGNMENT(.rel.*))

	.rela.dyn
	 *(SORT_BY_ALIGNMENT(.rela.*))

	/DISCARD/
	 *(SORT_BY_ALIGNMENT(.plt))
	 *(SORT_BY_ALIGNMENT(.iplt))
	 *(SORT_BY_ALIGNMENT(.got.plt))
	 *(SORT_BY_ALIGNMENT(.igot.plt))
	 *(SORT_BY_ALIGNMENT(.got))
	 *(SORT_BY_ALIGNMENT(.igot))
	 *(SORT_BY_ALIGNMENT(.irq_info))
	 *(SORT_BY_ALIGNMENT(.intList))
	                0x00000000                _image_rom_start = 0x0
	
	text            0x00000000     0x1100
	                0x00001000                . = 0x1000
	 *fill*         0x00000000     0x1000 
	                0x00001000                _vector_start = .
	 *(SORT_BY_ALIGNMENT(.exc_vector_table))
	 *(SORT_BY_ALIGNMENT(.exc_vector_table.*))

The linker.cmd file has this:
	_image_rom_start = (0x0 + 0x0);
	    text :
	 {
	 . = 0x1000;
	 _vector_start = .;
	 KEEP(*(.exc_vector_table))
	 KEEP(*(".exc_vector_table.*"))
	 KEEP(*(.gnu.linkonce.irq_vector_table))
	 KEEP(*(.vectors))
	 KEEP(*(.openocd_dbg))
	 KEEP(*(".openocd_dbg.*"))

	 KEEP(*(.kinetis_flash_config))
	 KEEP(*(".kinetis_flash_config.*"))
	 _vector_end = .;
	} > FLASH
Does the ". = 0x1000;" indicate the padding?
Thanks,
Jamie

Show quoted text

-----Original Message-----

Okay, if I was you I would have a look at the map file and try to figure out what it's putting there and why.

Sebastian Boe

#5890

"Does the ". = 0x1000;" indicate the padding?"


Yes, you would want to compare it to the source to see what it's trying to do, and possibly
how to make it stop.

________________________________________
From: Jamie Mccrae <Jamie.Mccrae@lairdconnect.com>
Sent: Thursday, April 4, 2019 3:13 PM
To: Bøe, Sebastian; devel@lists.zephyrproject.org
Subject: RE: Removing padding from generated hex files

Hi,
That's where I'm not sure on, I see the fill section but can't work out where it's coming from:
        Memory Configuration

        Name             Origin             Length             Attributes
        FLASH            0x00000000         0x00100000         xr
        SRAM             0x20000000         0x00040000         xw
        IDT_LIST         0x20040000         0x00000800         xw
        *default*        0x00000000         0xffffffff

        Linker script and memory map

        LOAD zephyr/CMakeFiles/kernel_elf.dir/misc/empty_file.c.obj
        LOAD zephyr/CMakeFiles/kernel_elf.dir/isr_tables.c.obj
        LOAD app/libapp.a
        LOAD zephyr/libzephyr.a
        LOAD zephyr/arch/arch/arm/core/libarch__arm__core.a
        LOAD zephyr/arch/arch/arm/core/cortex_m/libarch__arm__core__cortex_m.a
        LOAD zephyr/arch/arch/arm/core/cortex_m/mpu/libarch__arm__core__cortex_m__mpu.a
        LOAD zephyr/lib/libc/minimal/liblib__libc__minimal.a
        LOAD zephyr/boards/arm/nrf52840_pca10059/libboards__arm__nrf52840_pca10059.a
        LOAD zephyr/drivers/serial/libdrivers__serial.a
        LOAD zephyr/kernel/libkernel.a
        LOAD zephyr/CMakeFiles/offsets.dir/arch/arm/core/offsets/offsets.c.obj
        LOAD c:/gcc-arm/bin/../lib/gcc/arm-none-eabi/8.2.1/thumb/v7e-m/nofp\libgcc.a
                        0x00000020                _region_min_align = 0x20

        .rel.plt        0x00000000        0x0
         *(SORT_BY_ALIGNMENT(.rel.plt))
                        [!provide]                PROVIDE (__rel_iplt_start = .)
         *(SORT_BY_ALIGNMENT(.rel.iplt))
         .rel.iplt      0x00000000        0x0 zephyr/CMakeFiles/kernel_elf.dir/isr_tables.c.obj
                        [!provide]                PROVIDE (__rel_iplt_end = .)

        .rela.plt       0x00000000        0x0
         *(SORT_BY_ALIGNMENT(.rela.plt))
                        [!provide]                PROVIDE (__rela_iplt_start = .)
         *(SORT_BY_ALIGNMENT(.rela.iplt))
                        [!provide]                PROVIDE (__rela_iplt_end = .)

        .rel.dyn
         *(SORT_BY_ALIGNMENT(.rel.*))

        .rela.dyn
         *(SORT_BY_ALIGNMENT(.rela.*))

        /DISCARD/
         *(SORT_BY_ALIGNMENT(.plt))
         *(SORT_BY_ALIGNMENT(.iplt))
         *(SORT_BY_ALIGNMENT(.got.plt))
         *(SORT_BY_ALIGNMENT(.igot.plt))
         *(SORT_BY_ALIGNMENT(.got))
         *(SORT_BY_ALIGNMENT(.igot))
         *(SORT_BY_ALIGNMENT(.irq_info))
         *(SORT_BY_ALIGNMENT(.intList))
                        0x00000000                _image_rom_start = 0x0

        text            0x00000000     0x1100
                        0x00001000                . = 0x1000
         *fill*         0x00000000     0x1000
                        0x00001000                _vector_start = .
         *(SORT_BY_ALIGNMENT(.exc_vector_table))
         *(SORT_BY_ALIGNMENT(.exc_vector_table.*))

The linker.cmd file has this:
        _image_rom_start = (0x0 + 0x0);
            text :
         {
         . = 0x1000;
         _vector_start = .;
         KEEP(*(.exc_vector_table))
         KEEP(*(".exc_vector_table.*"))
         KEEP(*(.gnu.linkonce.irq_vector_table))
         KEEP(*(.vectors))
         KEEP(*(.openocd_dbg))
         KEEP(*(".openocd_dbg.*"))

         KEEP(*(.kinetis_flash_config))
         KEEP(*(".kinetis_flash_config.*"))
         _vector_end = .;
        } > FLASH
Does the ". = 0x1000;" indicate the padding?
Thanks,
Jamie

-----Original Message-----

Okay, if I was you I would have a look at the map file and try to figure out what it's putting there and why.