Read-write configuration data

Mick Davis mickd at
Fri Nov 9 03:00:44 UTC 2012

How do you mean read-only?

That seems to be too broad a question to answer definitively.

It would seem fine for the simple self-contained RTEMS + single app case.

But where RTEMS fits for us is with flexible devices, where there's a 
lot of runtime configuration during RTEMS start up, and loadable modules.

Hopefully RTEMS will get an elf loader in the future and this will be 
true more generally.

So for instance, I specifically setup rtems_telnetd_maximum_ptys from a 
configuration at runtime, depending on what else is configured.

In the most recent apps I've been using the unlimited system for the 
number of tasks + queues etc.  But I can easily imagine going back to a 
system of setting up the Configuration_RTEMS_API before RTEMS starts 
with the number of resources based on an installed config.

Device_drivers seems like something that would often get setup depending 
on available hardware.

The location and size of the heap is setup by the bootloader for us, 
after all images have been put into memory.

On the other hand, I have sometimes wondered if fixing the tick length 
would help performance.

I guess I don't know exactly what you plan.  And it might be OK if 
they're just read only after RTEMS is up and running, perhaps using the 
MMU.  But yes, in general, I would probably have an objection.

On 08/11/12 23:48, Sebastian Huber wrote:
> Hello,
> a lot of the RTEMS configuration is read-write data.
> Configuration_POSIX_API
> Configuration_RTEMS_API
> Device_drivers
> _POSIX_Threads_Initialize_user_threads_p
> rtems_fs_init_helper
> rtems_libio_init_helper
> rtems_libio_number_iops
> rtems_libio_supp_helper
> rtems_malloc_dirty_helper
> RTEMS_Malloc_Heap
> rtems_malloc_statistics_helpers
> rtems_maximum_priority
> rtems_minimum_stack_size
> _RTEMS_tasks_Initialize_user_tasks_p
> rtems_telnetd_maximum_ptys
> _Scheduler
> Are there objections to make them read-only?


Mick Davis
Goanna Technologies Pty Ltd
+61 8 9444 2634

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