Read-write configuration data

Chris Johns chrisj at
Fri Nov 9 03:30:31 UTC 2012

Mick Davis wrote:
> How do you mean read-only?

Maybe this helps ....


> 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?

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