Reminder: Zephyr Project: Dev Meeting

When: Thursday, 26 March 2020, 8:00am to 9:00am, (GMT-07:00) America/Los Angeles

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Here’s the agenda topics for this week:

* Review PR’s tagged with dev-review
* use of PRE_KERNEL_1/PRE_KERNEL_2...
* Pinmux/pinctrl (Piotr/Erwan)
* Any topics anyone else has

- k

Hi all,

I was wondering about the state of crypto APIs in Zephyr and whether it makes sense to move them forward or instead we should consider simply using the mbed TLS set of APIs as Zephyr's crypto API.

The reason I say this is that today we have include/crypto/cipher.h which abstracts ciphers, but that's about it. Most users in the code seem to use mbed TLS APIs directly when they require crypto functionality (with the exception of Bluetooth which can use TinyCrypt or mbed TLS and has its own abstraction) with only the IEEE 802.15.4 stack using cipher.h.
mbed TLS is a recognized crypto API that (as far as I know) can be used with or without the actual mbed TLS implementation, so I question the need to define our own in this particular case, although I might be missing key information. Unless I am mistaken one can implement hardware-accelerated or custom or proprietary implementations of crypto functions and shim them so that they expose the mbed TLS API.

In any case I do believe this is something that needs discussion since the current usage in the tree is inconsistent and the subset of APIs defined in include/crypto is very small.

If we did decide to use mbed TLS as an API we would then also need to discuss how to go about it, since mbed TLS is today an (optional) module and therefore the header files themselves are not included in the main zephyr tree.

Input welcome!

Regards,

Carles

Reminder: Zephyr Project: APIs

When: Tuesday, 24 March 2020, 9:00am to 10:00am, (GMT-07:00) America/Los Angeles

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Hello,

On Tue, 24 Mar 2020 11:25:48 +0200
"Jukka Rissanen" <jukka.rissanen@linux.intel.com> wrote:

Hi Darryl,

I think it is more of a historical relic than a purpose design. There
has not been any reports that this have caused issues. Patches are
welcome of course.

Perhaps it could be rephrased differently: net_buf is more like Zephyr's
internal system object. Where it's used currently, thread
synchronization is expected(*) to happen on different level(s), and
net_buf itself is kept lightweight and optimized. Perhaps that can be
changed, but effects on existing subsystems using net_buf should be
considered.

(*) That doesn't mean there're no bugs, so reproducible bugreports are
welcome.

Cheers,
Jukka


On Sun, 2020-03-22 at 17:39 -0700, Darryl Gamroth wrote:

Hi all,

I was looking at using net_bufs for an application broadcasting
reference counted buffers to multiple threads and I noticed the
reference counting is not atomic. I'm curious, is this by design?

Thanks.

--
Best Regards,
Paul

Linaro.org | Open source software for ARM SoCs
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Hi all,

Note: This is the last week where the meeting takes place at 17h CET. Next week we go back to 18h CET.

Today's topics:

- How to document standalone drivers like the enc28j60 (Piotr)

- Upgrade the hwinfo API to stable
- PR: https://github.com/zephyrproject-rtos/zephyr/pull/23661

- RTC API proposal
- PR: https://github.com/zephyrproject-rtos/zephyr/pull/23526/commits/2880ee02b0f2fd91d897d8a11a4cbdefe87a19b0

- Naming in the async_notify module
- PR: https://github.com/zephyrproject-rtos/zephyr/pull/23601

Additional items in the "Triage" column in the GitHub project may be discussed if time permits.
If you want an item included in the meeting, please add it to the GitHub project.

https://github.com/zephyrproject-rtos/zephyr/wiki/Zephyr-Committee-and-Working-Group-Meetings#zephyr-api-discussion
https://github.com/zephyrproject-rtos/zephyr/projects/18
https://docs.google.com/document/d/1lv-8B5QE2m4FjBcvfqAXFIgQfW5oz6306zJ7GIZIWCk/edit

Regards,

Carles

Hi Darryl,

I think it is more of a historical relic than a purpose design. There
has not been any reports that this have caused issues. Patches are
welcome of course.

Cheers,
Jukka

Hi,

Iam using nrf52840 development board, developing software using zephyr.
In software development iam using bluetooth as a peripheral and uart in interrupt mode(to get data from other module), when iam trying to run both interfaces the getting below errors and iam included watchdog timer so after sometime it is restarting.

Hi all,

I was looking at using net_bufs for an application broadcasting reference counted buffers to multiple threads and I noticed the reference counting is not atomic. I'm curious, is this by design?

Thanks.

Dear all,

This email is a request to change the stability of the Hardware Information API from "unstable" to "stable".

Pull-request: #23661
Discussion in the API meeting takes place on Tuesday, March 24th.

If there are any objections, please comment on the PR or attend to the API meeting.

Kind regards,

--
Alexander Wachter

The guy who introduced this API

Reminder: Zephyr Project: Dev Meeting

When: Thursday, 19 March 2020, 8:00am to 9:00am, (GMT-07:00) America/Los Angeles

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Zephyr Toolchain Working Group

When:
Thursday, 19 March 2020
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Agenda:

* Review any open PR / issues with dev-review label
* Device Tree update / next steps (Kumar & Marti)
* Power Management thoughts / initial ideas / plans (Peter)
* Pinmux / DT (Piotr)

If you have anything you’d like to add let me know

Thanks

- k

Reminder: Zephyr Toolchain Working Group

When: Thursday, 19 March 2020, 7:00am to 8:00am, (GMT-07:00) America/Los Angeles

Where:https://zoom.us/j/967549258

View Event

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Hi,

Thanks for clarification.

Ravi

Hello,

On Wed, 18 Mar 2020 11:34:00 +0200
"Ravi kumar Veeramally" <ravikumar.veeramally@linux.intel.com> wrote:

Hi,

what should be the return value or behavior of socket poll() call in
case of TCP socket is closed from peer side.

If a peer closes TCP connection from its side, it's effectively an
analog of EOF condition. In this case, poll() should return POLLIN.
This will cause a client to issue a recv()/read() call, which will
return 0, and will let a client detect the EOF condition.

This is one of the "most basic" of "not immediately obvious" API
contracts re: sockets and polling. It's definitely something like that,
because quickly looking for normative references in the POSIX standard,
I can't find them, e.g. in
https://pubs.opengroup.org/onlinepubs/9699919799/functions/poll.html
this particular case isn't described (some other "not immediately
obvious" cases are). So, it's a kind of common knowledge, and a lot of
software relies on that behavior (well, it's not possible to write
async socket code without it). If you google for it, you should be able
to find a lot of references.

Note that there's also a POLLHUP flag, behavior of which in regard to
sockets is "less clear" and "somewhat of a gray area".

As per
https://github.com/zephyrproject-rtos/zephyr/blob/master/subsys/net/lib/sockets/sockets.c#L1018,
zsock_poll_prepare_ctx() call returns -EALREADY.

zsock_poll_prepare_ctx() is an internal function, which uses a special
internal API contract, where particular error codes are used to signal
very specific conditions. -EALREADY is one of such codes. It doesn't
reach public API clients (and doesn't have the same meaning as POSIX
EALREADY error).

But
https://github.com/zephyrproject-rtos/zephyr/blob/master/subsys/net/lib/sockets/sockets.c#L1088.
Return value of z_fdtable_call_ioctl() function call handler assumes
"If POLL_PREPARE returned with EALREADY, it means it already detected
that some socket is ready."

Right, to achieve the behavior described above.

I did a simple test with few modifications in echo-client and
echo-server in net tools. echo-server closes the client connection.
poll(fds, nfds, 0) call returns "> 0" and error value set to 0. But
send failed with return value -ve and error value set to ESHUTDOWN.

That sounds *about* right. Except that POSIX requires EPIPE to be
returned trying to write to a socket with underlying connection closed.
Or to be more exact, with the quote
(https://pubs.opengroup.org/onlinepubs/9699919799/functions/send.html):

-------
[EPIPE]
The socket is shut down for writing, or the socket is
connection-mode and is no longer connected. In the latter case, and if
the socket is of type SOCK_STREAM or SOCK_SEQPACKET and the
MSG_NOSIGNAL flag is not set, the SIGPIPE signal is generated to the
calling thread.
-------

So, if we return ESHUTDOWN, we should change that to EPIPE.


If your mail trails to the ultimate question of "how to detect
peer-closed socket if we called poll with POLLOUT?", then to keep it
short:

a) Hmm, I don't have an answer right away, though I bet I used to
consider it (likely outside Zephyr context).
b) I bet that's where POLLHUP return status kicks in.
c) In all cases like that, where we can't "extract" normative behavior
description from POSIX, we should check and follow the behavior of a
well-know implementation, and that's definitely Linux.

Any thoughts @rlubos <https://github.com/rlubos> @pfalcon
<https://github.com/pfalcon>?

Please don't hesitate to cc: me on mails like this, I may sometimes not
check the mailing list for a few days.

Regards,

Ravi.

[]

--
Best Regards,
Paul

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