Secure bootloader chain + two-stage upgradable bootloader MCUBOOT

[Siddharth Kachhia]

I am working with nRF connect SDK with nRF5340DK. I am compiling code using nRF connect (ncs-1.8.0) for VS code with nrf5340dk_nrf5340_cpuapp board.

prj.conf as below,

CONFIG_BOOTLOADER_MCUBOOT=y

CONFIG_MCUMGR=y

CONFIG_SECURE_BOOT=y

Using this I can enabling two-stage bootloader, here are the log,

 

*** Booting Zephyr OS build v2.7.0-ncs1 ***

Attempting to boot slot 0.

Attempting to boot from address 0x8200.

Verifying signature against key 0.

Hash: 0x12...93

Firmware signature verified.

Firmware version 1

Booting (0x8200).

*** Booting Zephyr OS build v2.7.0-ncs1 ***

I: Starting bootloader
I: Primary image: magic=good, swap_type=0x3, copy_done=0x1, image_ok=0x1
I: Secondary image: magic=unset, swap_type=0x1, copy_done=0x3, image_ok=0x3
I: Boot source: none
I: Swap type: none
I: Primary image: magic=unset, swap_type=0x1, copy_done=0x3, image_ok=0x3
I: Secondary image: magic=unset, swap_type=0x1, copy_done=0x3, image_ok=0x3
I: Boot source: none
I: Bootloader chainload address offset: 0x28000
I: Jumping to the first image slot
*** Booting Zephyr OS build v2.7.0-ncs1 ***

I can firmware upgrade over-the-air (FOTA) for application using app_update.bin file.

Question:

1) How can I upgrade the second stage bootloader(MCUBoot bootloader)?

2) Which bin file to upload for upgrade the second stage bootloader?

[Hung Bui]

Hi Siddharth, 

I would suggest to have a look at this case to have an idea of how it should be handled: https://devzone.nordicsemi.com/f/nordic-q-a/67024/nrf9160-questions-related-to-immutable-mcuboot-application/274813#274813

Then you can have a look at this case , our coworker has created a working example: 

https://devzone.nordicsemi.com/f/nordic-q-a/85539/update-mcuboot-with-smp/358748

[Siddharth Kachhia]

Hi Hung,

I have tried your coworker example : https://devzone.nordicsemi.com/f/nordic-q-a/85539/update-mcuboot-with-smp/358748

but its not updating MCUBOOT!!

 For, testing I had follow below steps,

I make a change to MCUBoot, for example add a log in $NRF_CONNECT_SDK/bootloader/mcuboot/boot/zephyr/main.c.

Build again, and upload the new image using mcumgr:

mcumgr conn add acm0 type="serial" connstring="dev=/dev/ttyACM0,baud=115200,mtu=512"
mcumgr -c acm0 image list
mcumgr -c acm0 image upload build/zephyr/signed_by_mcuboot_and_b0_s1_image_update.bin
mcumgr -c acm0 image list

Copy the hash of the newly uploaded image, and use it to confirm it, making the new image run at next reboot, such as:

mcumgr -c acm0 image confirm 2348de4f84cb19c1c2721662ad1275da5c21eca749da9b32db20d2c9dffb47c0

Then reboot the Developement Kit. This will load the new MCUBoot image its slot. Reboot the Developement Kit again to load using the new version of MCUBoot.

If I miss any steps let me know please.

I did not Disable the Mass Storage feature on the device. is this required to do that?

Why required Disabling the Mass Storage feature on the device? 

Also I have one questions,

How we can use both stage bootloader as MCUBOOT? as shown in below ,I am talking about second options.

Bootloader	Can be first-stage	Can be second-stage	Key type support	Public key revocation	SMP updates	Downgrade protection	Versioning	Update methods (supported by nRF Connect SDK)
nRF Secure Immutable Bootloader	Yes	No	See list	Yes	No	Yes	Monotonic (HW)	Dual slot execute in place (XIP)
MCUboot	Yes	Yes	See imgtool	No	Yes	Yes	Semantic (SW)	Image swap - single primary

[ErDarshan]

Thanks for the update. Let us know if you require any help from ourside.

[Siddharth Kachhia]

Hi Simon,

Have you completed the implementation?

[Simon]

Sorry for the delay.

Currently I'm able to do the following 

• 1. Update mcuboot through the application
• 2. Update the application through the application

It is not possible to do the following

• 3. Update the network core through the application (application on app core) while nRF Secure Immutable Bootloader (NSIB) is enabled

Without enabling NSIB, it is possible to update the network core through the application, but NSIB is needed in order to update mcuboot.

I think 3 is related to this https://devzone.nordicsemi.com/f/nordic-q-a/84786/nrf5340-nrf-secure-immutable-bootloader-and-network-core-bootloader. I will ask Amanda and the developers tomorrow what the current state is

Best regards,

Simon

[Siddharth Kachhia]

Hi Simon,

Thanks for the update. waiting for your response. 

[Simon]

I think I found a fix for being able to update the network core while NSIB is enabled. Apply this patch to bootloader/mcuboot (associated with NCS v1.9.0):

diff --git a/boot/bootutil/src/loader.c b/boot/bootutil/src/loader.c
index d5c370c4..7b2d823b 100644
--- a/boot/bootutil/src/loader.c
+++ b/boot/bootutil/src/loader.c
@@ -926,6 +926,7 @@ boot_validated_swap_type(struct boot_loader_state *state,
         vtable = (uint32_t *)(vtable_addr);
         reset_addr = vtable[1];
 #ifdef PM_S1_ADDRESS
+        if(reset_addr < PM_CPUNET_B0N_ADDRESS){ 
         const struct flash_area *primary_fa;
         int rc = flash_area_open(flash_area_id_from_multi_image_slot(
                     BOOT_CURR_IMG(state),
@@ -942,6 +943,7 @@ boot_validated_swap_type(struct boot_loader_state *state,
             */
             return BOOT_SWAP_TYPE_NONE;
         }
+        }
 #endif /* PM_S1_ADDRESS */
     }
 #endif /* PM_S1_ADDRESS || CONFIG_SOC_NRF5340_CPUAPP */

I will do some more testing and provide you with the complete sample and the patch.

Best regards,

Simon

[Siddharth Kachhia]

Hi Simon,

Thanks for the update. I will try with your changes and let you know the result.

For upgrading the network core, which flash partition your are using to store the bin file?

As shown in above image, are you using image_3 partition for storing the network core bin file?

[Simon]

Actually, the network image should be put into mcuboot secondary slot, image_1(same as where the application goes).

Then mcuboot will look at the reset_addr to see if it's a network core update (this happens in the loader.c ) . If that is the case, it will transfer the image to the network core using pcd_network_core_update().

I will provide you with a complete application tomorrow, that can update the network core, the application and the mcuboot.

Best regards,

Simon

[Simon]

If you use this sample, along with the patch I provided you with, you should be able to:

1. Update the network core (Using net_core_app_update.bin) 
2. Update the application core (Using app_update.bin)
3. Updating 2nd stage MCUboot bootloader (Using signed_by_mcuboot_and_b0_s1_image_update.bin)

I will provide some detailed instructions in https://github.com/simon-iversen/ncs_samples/tree/master/update_mcuboot_app_and_netcore how to do 1-3, later on today.

Best regards,

Simon

[Siddharth Kachhia]

Thanks for the sample. I will test and implement in our code and let you know.

Is your sample works with ncs sdk V1.8.0?

[Simon]

I have updated the README in Update application core (main application and MCUboot) and the network core of the nRF5340 by adding some instructions how to perform a DFU update of respectively the main application, mcuboot and the network core

Siddharth Kachhia said:

Is your sample works with ncs sdk V1.8.0?

It is tested using NCS v1.9.0. Hopefully it works with v1.8.0 as well. Let me know if it doesn't

Best regards,

Simon