Sample project to demonstrate kernel space and user space

RE: Sample project to demonstrate kernel space and user space

Ubaid_M — Sat, 29 Oct 2022 12:17:21 GMT

Sure,Thanks

RE: Sample project to demonstrate kernel space and user space

Simon — Thu, 27 Oct 2022 12:56:15 GMT

I'm not sure about this question. I will be gone now for a long time, so would you be able to open a new DevZone ticket about this?

Best regards,

Simon

RE: Sample project to demonstrate kernel space and user space

Ubaid_M — Thu, 27 Oct 2022 11:58:48 GMT

Thanks Simon, That was largely helpful.

As a last query of mine, if we take an example of nrf52840dk, which has onboard QSPI external flash.

Can I treat the internal flash here in, to work on kernel space only, while having the QSPI external flash to work on user space..?

If possible, has such a thing been done..?
Please help me with any sample project available for the same.

Thanks,

RE: Sample project to demonstrate kernel space and user space

Simon — Thu, 27 Oct 2022 11:46:49 GMT

[quote user="Ubaid_M"]1. What would be the ideal way to communicate between kernel threads and user threads..? Is it message queues..?[/quote]

Yes, that could work. See RE: Recommended best practice for a multithreaded sensor for other ways of thread communication.

[quote user="Ubaid_M"]2. Does it make sense if I treat all peripheral (SPI, I2C, UART etc,.) handlers as individual kernel space threads and all application algorithms that consume the peripheral data as user space threads..?[/quote]

That could work. Here are some example use cases of Zephyr' user mode feature:

The kernel can protect against many unintentional programming errors which could otherwise silently or spectacularly corrupt the system.
The kernel can sandbox complex data parsers such as interpreters, network protocols, and filesystems such that malicious third-party code or data cannot compromise the kernel or other threads.
The kernel can support the notion of multiple logical “applications”, each with their own group of threads and private data structures, which are isolated from each other if one crashes or is otherwise compromised.

Best regards,

Simon

RE: Sample project to demonstrate kernel space and user space

Ubaid_M — Wed, 26 Oct 2022 17:38:45 GMT

Thank you Simon,

1. What would be the ideal way to communicate between kernel threads and user threads..? Is it message queues..?

2. Does it make sense if I treat all peripheral (SPI, I2C, UART etc,.) handlers as individual kernel space threads and all application algorithms that consume the peripheral data as user space threads..?

Thanks,
Ubaid

RE: Sample project to demonstrate kernel space and user space

Simon — Wed, 26 Oct 2022 14:33:17 GMT

Just omit the K_USER option when creating the thread. See the following sample:

devzone.nordicsemi.com/.../user_5F00_supervisor_5F00_mode_5F00_test.zip

It should give the following output:

*** Booting Zephyr OS build v3.1.99-ncs1  ***
user_function: UserSpace! (nrf52840dk_nrf52840)
supervisor_function: privileged mode. (nrf52840dk_nrf52840)

Best regards,

Simon

RE: Sample project to demonstrate kernel space and user space

Ubaid_M — Wed, 26 Oct 2022 12:09:53 GMT

Hi,

Can you point me towards thread creation in kernel space similarly.
I want to have both kernel space and user space threads in my app.

[quote userid="72692" url="~/f/nordic-q-a/93253/sample-project-to-demonstrate-kernel-space-and-user-space/392611"]In order to drop a thread down to user mode[/quote]

Thanks,

RE: Sample project to demonstrate kernel space and user space

Simon — Wed, 26 Oct 2022 12:05:34 GMT

As mentioned in the zephyr thread documentation, threads run in supervisor mode by default

In order to drop a thread down to user mode, set CONFIG_USERSPACE=y in the prj.conf file and crete the thread like done in the hello_world_user sample

You need to use the K_USER option when creating the thread

Best regards,

Simon