[Sound-open-firmware] sof-logger status on SOF with Zephyr

[Kai Vehmanen]

Hi,

On Mon, 29 Aug 2022, Girdwood, Liam R wrote:

> On Mon, 2022-08-29 at 10:35 +0000, Daniel Baluta wrote:
>> What is the plan for sof-logger with SOF-Zephyr? Is it working on
>> Intel platforms?

we do have sof-logger working as well, but this has the big limitation in 
that you will only see logs from SOF. E.g. all logs in Zephyr side 
drivers and core OS code are not visible in sof-logger output.

So you can now also compile SOF with CONFIG_ZEPHYR_LOG=y which routes
all SOF-side log statements to Zephyr logging subsystem.

For Intel HW, the simplest way to get these logs out are with
CONFIG_LOG_BACKEND_ADSP=y
This routes an ascii/text trace over SRAM window 2, so you can 
do "cat /sys/kernel/debug/sof/etrace" to get the logs out with the SOF 
Linux driver.

But this is still not on par with the old sof-logger, so we are working on 
better backends and...:

> Zephyr uses a Mipi SYS-T standards for logging and tracing and hence
> SOF will also use the same standard when built with Zephyr.

For encoding, we are planning to use Sys-T and this is already well 
supported in Zephyr upstream (CONFIG_LOG_MIPI_SYST_ENABLE). We've also 
tested other encodings, including plain ascii and the Zephyr log 
dictionary.

For log transport, we've just added probes support:
https://github.com/thesofproject/sof/pull/6072 (merged)

.. this should be reusable across multiple hw targets. Basicly we use
the same transport as is used to transfer PCM probes, to get logs out, and 
the logs encoding can be anything that Zephyr supports.

The tooling will require some love still. Currently to get old 
sof-logger's user-experience (but with Zephyr logs included), you need to 
use a combination of debugfs, sof-probes and crecord, but we are planning 
to improve the tooling still.

Br, Kai