Flash Image API on Network Core

RE: Flash Image API on Network Core

nkost — Thu, 05 Jan 2023 12:08:09 GMT

devzone.nordicsemi.com/.../flash_5F00_access_5F00_nvmc_5F00_s.zip

Hi Naeem

Attached you can find the project. I simply took the project that I provided earlier, removed MCUboot as it is not needed and changed the main on the NetCore to write to flash.

After flashing it to the nRF5340 DK, I read the flash address that was overwritten using nrfjprog.

RE: Flash Image API on Network Core

Naeem Maroof — Thu, 05 Jan 2023 11:31:08 GMT

Hi nkost,

Can you please share your project/code where you are successfully accessing the app-core flash region using the secure nvmc.

RE: Flash Image API on Network Core

nkost — Thu, 29 Dec 2022 09:35:47 GMT

I've found a way to do what I want, but there are still open questions.

It works when I access the AppCore's NVMC over its Secure base address (0x50039000) from the NetCore using the nrfx HAL. From my understanding it should also work, when accessing the AppCore's NVMC over its Non-Secure base address (0x40039000), when the DCNF and SPU settings are configured accordingly, but I can't get that to work properly (meaning, I can access and configure the peripheral, but when trying to write to the flash, I get the above described fault).

From the information in the documentation, both ways should work. The question that remains is: How does it work?

RE: Flash Image API on Network Core

Naeem Maroof — Sun, 04 Dec 2022 20:15:14 GMT

Hi nkost,

I was not able to do it successfully, and we don't have any specific example/sample for your case as well.

RE: Flash Image API on Network Core

nkost — Tue, 29 Nov 2022 09:15:42 GMT

Hi Naeem,

Thank you for your answer.

The network core can access application core resources (flash, RAM, and peripherals) when granted permission through the application's DCNF and SPU settings.

This is what I need but does not yet work (the access to the flash, I don't need access to the RAM and the peripherals).

I know about the IPC, but that is not what I need. I want to access the flash directly from the network core and not to send the data from the network core through IPC to the application core.

Did you find a way to get the example from above to work?

RE: Flash Image API on Network Core

Naeem Maroof — Tue, 29 Nov 2022 09:02:57 GMT

Hi nkost,

Thank you for being patient. I have gone through documentation again.

- Yes, writing flash is managed by the NVMC

- For the nrf4350, the application core memory is mapped to the network core memory map

- This means that the network core CPU can access and use the application core memory for shared memory communication.

- Even then, the application core can restrict network core access through the domain configuration (DCNF) PROTECT registers. Access to secure memory or peripherals is also prevented when the network core is marked as non-secure

- The network core can access application core resources (flash, RAM, and peripherals) when granted permission through the application's DCNF and SPU settings. A small portion of the application core RAM is dedicated to the exchange of messages between the application and network cores.

- We have IPC (interprocessor communication) periphereal that is used to send and receive events between MCUs.

- An IPC event often does not contain any data itself, it is used to signal other MCUs that something has occurred.

- Data can be shared through shared memory, for example in the form of a software implemented mailbox, or command/event queues.

- It is up to software to assign a logical functionality to an IPC channel. For instance, one IPC channel can be used to signal that a command is ready to be executed, and any processor in the system can subscribe to that particular IPC channel and decode/execute the command.

You can look more into the IPC and using OpenAmp.

Regards,

Naeem

RE: Flash Image API on Network Core

nkost — Fri, 25 Nov 2022 08:11:08 GMT

Hi Naeem,

Some additional information that might help:

I've tried the same as in the example above with two variations:

- writing to other adresses in the address space of the AppCore,

- removing MCUboot from the AppCore.

Both lead to the same fault as before.

RE: Flash Image API on Network Core

Naeem Maroof — Tue, 22 Nov 2022 12:28:09 GMT

Hi nkost,

I have received your sample, and can reproduce the error. I tried to check for writability before performing actual write. The address seems writable but still the netcore reboots and shows the bus fault. I will try to figure out the cause / problem, and will let you know accordingly.

Regards,

Naeem

RE: Flash Image API on Network Core

nkost — Mon, 21 Nov 2022 07:56:48 GMT

Hi Naeem,

I tried to do the same using the NVMC HAL function. Trying to write to the address results in a Bus Fault (the instruction that assigns the value to that address causes this fault: *(volatile uint32_t *)addr = value; in the function nvmc_word_write). I've added the minimal project of this test.

devzone.nordicsemi.com/.../flash_5F00_access_5F00_mcuboot_5F00_nrfx.zip

RE: Flash Image API on Network Core

nkost — Fri, 18 Nov 2022 16:19:01 GMT

Hi Naeem,

Yes, when trying to use flash_area_write I get that error. (I tried using that bcs. the higher-abstraction libraries/APIs didn't work, as described above).

The flash write:

// ...
err = flash_area_open(area_id, &fa);
if (err) {
  return err;
}

flash_area_write(&fa, 0, data, dataLen);

I added the following overlay (which I inherited from this thread):

/{
    chosen {
        zephyr,flash0 = &flash0;
    };
};

&flash_controller {
    label = "NRF_FLASH_APP";
    flash0: flash@0 {
        reg = <0x00000000 DT_SIZE_K(1024)>;
        compatible = "soc-nv-flash";
        label = "NRF_FLASH_APP_1";
        erase-block-size = <4096>;
        write-block-size = <4>;
        partitions {
            compatible = "fixed-partitions";
            #address-cells = <1>;
            #size-cells = <1>;
            app_2_partition: partition@84000 {
                label = "app-2";
                reg = <0x00084000 0x40000>;
            };
        };
    };
};

I don't have the time at the moment to create a minimal example. I will do so when I find the time.

RE: Flash Image API on Network Core

Naeem Maroof — Fri, 18 Nov 2022 15:14:46 GMT

Hello nkost,

Alright, so the error you are facing is "invalid address".

How are you performing the flash write? are you using nvmc?

I would like to see your code and the method to reproduce the error.

(preferably you can send your minimal project zip).

Regards,

Naeem

RE: Flash Image API on Network Core

nkost — Fri, 18 Nov 2022 13:25:37 GMT

Hi Naeem

Thanks four your answer. The setup you described is the one I use. I now need to write to the "Secondary Slot" in the AppCore Flash from the "Net core app". The problem is that the address of the "Secondary Slot" is not known in the "Net core app".

This flash should be accessible from the NetCore (according to the Product Specification of nRF5340, Section 3.2 Fig. 2 Memory Map and Section 6.4 Memory: "The network core can access application core resources (flash, RAM, and peripherals) when granted permission through the application's DCNF and SPU settings.") When I try to write to this address using the function flash_area_write, it returns with an error "invalid address" (Permissions are not the problem).

How can I access the flash of the AppCore from the NetCore?

RE: Flash Image API on Network Core

Naeem Maroof — Fri, 18 Nov 2022 13:10:44 GMT

Hi nkost,

Thank you for your patience.

Coming to your query:

[quote user=""]When I try to use the Flash Image API on the Network Core I get build errors. The problem seems to be that some symbols are not defined, as there is no MCUboot bootloader on the Network Core (but there is one on the Application Core).[/quote]

Well, we have two bootloaders for 5340 as it has two cores, one for the app core (called MCUboot) and other for the network-core, called b0n which is an immutable first-stage bootloader that can update the application firmware on the network core of the nRF5340 SoC.

I suggest to look at netboot sample to see the use-case and the configurations.

[quote user=""]What is the intended way to use the Flash Image API to write image data from the Network Core to an image slot of the Application Core?[/quote]

Flash Image Api is specific example use. Let us talk about writing image from the network core to an image slot of the app core. For such a purpose, you need to do a multi-image build. It is well described here: Multi-Image Build

Hope it helps,

Regards,

Naeem

RE: Flash Image API on Network Core

Naeem Maroof — Fri, 18 Nov 2022 09:10:14 GMT

Hi nKost,

I have been assigned this ticket and will look into this case, and accordingly will come back to you soon.

Regards,
Naeem

RE: Flash Image API on Network Core

nkost — Thu, 17 Nov 2022 16:27:59 GMT

I had a look at the underlying Stream Flash module. When the overlay file of the Nework Core is adjusted to introduce the correct address space, the flash_area_open function of the Flash Map API is able to find the correct partition. But stream_flash_init fails on the comparison of offset+size and inspect_flash_ctx.total_size.

Any thoughts? (I already got four notifications that an engineer has been assigned to this ticket, but there's no answer yet.)

RE: Flash Image API on Network Core

nkost — Wed, 09 Nov 2022 21:29:39 GMT

Could it be that the image slot of the application core is not known in the network core because it is not defined as a flash region? If yes, how would you solve that?