Why not use the ETM?
-----Original Message-----
From: Gregory Nutt [mailto:spudan...@gmail.com]
Sent: Friday, June 12, 2020 5:03 PM
To: dev@nuttx.apache.org
Subject: NXView
Hi, List,
I have been contemplating a NuttX-based Open Source project today and I
am interested in seeing if anyone is willing to participate or, even if
not, if anyone has any insights or recommendations that could be useful.
Basically, I am thinking of a NuttX tool to monitor the internal state
of the OS. This would be conceptually similar to Segger SystemView or
Wind River WindView: A host basic graphical tool that exposes the
internal behavior of tasks and threads within the OS in a "logic
analyzer format":
1. Horizontal rows would be indicate the state of each task, running or
block (and if blocked why/)
2. Each arranged vertically by task/thread priority so that the highest
priority task is the first row and the lowest priority task is the
bottom row.
3. Annotation to indicated events: Interrupts, semaphore operations,
spinlock operations, etc.
4. This display should be realtime (with a lag, of course) and should
scroll to the right as time elapses. It should be possible to
capture and save the event data for subsequent offline analysis.
Additional analytic displays could be considered in the future.
The hardware I am thinking to accomplish this would be an inexpensive
FT245RL board which connects to the target via an 8-bit parallel
interface and to the host via a USB 2.0 interface. The target side is
essentially a FIFO: OS events would be written to the FT245RL FIFO and
transferred to the host via USB 2.0.
The OS instrumentation is already in place to accomplish this. This is
controlled by CONFIG_SCHED_INSTRUMENTATION and related configuration
options that you can see in sched/Kconfig. The target side effort is then:
1. Configure the parallel interface to the FT245RL's FIFO. This would
likely be FSMC for an initial STM32 implementation.
2. Develop the simple logic to encode the instrumented events and to
pass them to host visa that FIFO.
Drivers and configuration tools for the host side are already available
from the FTDI website. Becoming familiar with these tools and
integrating the host-side interface would be another task.
The final task, the one that is the most daunting to me, is the
development of the substantial host-side graphics application that would
receive the OS instrumentation data and produce the graphic
presentation. I would think that such an application would be a C++
development and would be usable both on Windows and Linux.
I believe that such a tool would be a valuable addition to the NuttX
ecology. I think that such a tool would move NuttX from a basic,
primitive open source OS project and into full competition with
commercial products (in terms of features and usage... we are not
actually in competition with anyone).
Is this something that would be interesting to anyone? Does anyone have
any input or advice? If there is any interest I think that we should
create a small development team to make this happen. If that team is
small enough, I would be happy to provide common development hardware
(STM32 and FT245RL boards from China, or course).
What say ye?
Greg
