On 31/08/2020 23:15, Joel Sherrill wrote:
On Fri, Aug 21, 2020 at 6:51 AM Sebastian Huber
<sebastian.hu...@embedded-brains.de
<mailto:sebastian.hu...@embedded-brains.de>> wrote:
In contrast to rtems_task_create() this function creates a task with a
user-provided task storage area.
And all the creation parameters are in a structure which this log
doesn't mention.
Ok, I will add this to the commit message.
How is the user supposed to know how large the "task storage area" should be
The sp01 modifications seem to be a bit deceptive because the area is
just declared
in terms of stack size. I would expect some user facing macros that
capture the
size required for a non-FP and FP task. If FP is all tasks, then both
would give
the same base value. Perhaps even take the requested stack size.
Ok, we already have an internal CONTEXT_FP_SIZE. What about adding an
RTEMS_TASK_FLOATING_POINT_CONTEXT_SIZE define which can be used to
deterime the size of the task storage area?
How does the user account for any memory that is needed for alignment?
Declaring a byte array is almost certainly not aligned sufficiently for a
structure with larger elements and the stack itself may need to be cache
line size aligned.
The parts allocated from the storage area do their own alignment. We
could add an RTEMS_TASK_STORAGE_ALIGNMENT define to help to reduce
memory waste.
I spotted multiple places in this patch where variables and parameters
are not aligned properly.
Which places?
But more important than formatting, I think the user facing part is too
error
prone as it appears to be defined. It still counts as a user facing task
which
means confdefs.h will include it in its stack calculations and that is used
to reserve memory which will never be used. Similarly maximum tasks
is used to reserve work space memory for various structures.
This is one of the last missing pieces to get rid of the workspace for
certain application configurations. Mixing rtems_task_create() and
rtems_task_create_build_whatever() is not recommended. If you really
want to mix the functions, then the task stack space configuration is a
bit more difficult. You can for example adjust the size via
CONFIGURE_MEMORY_OVERHEAD.
I will add this as a note to the documentation.
I don't think this one is ready. It needs API discussion more than basic
feature discussion.
It would be nice to know your preference with respect to the function name.
--
Sebastian Huber, embedded brains GmbH
Address : Dornierstr. 4, D-82178 Puchheim, Germany
Phone : +49 89 189 47 41-16
Fax : +49 89 189 47 41-09
E-Mail : sebastian.hu...@embedded-brains.de
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Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.
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