Use of rtems_fdt_* and sp01

[Joel Sherrill]

On Fri, Nov 18, 2022, 8:49 AM Kinsey Moore <kinsey.moore at oarcorp.com> wrote:

>
> On Fri, Nov 18, 2022 at 12:44 AM Sebastian Huber <
> sebastian.huber at embedded-brains.de> wrote:
>
>> On 18/11/2022 06:32, Kinsey Moore wrote:
>> > On Thu, Nov 17, 2022 at 4:49 PM Chris Johns <chrisj at rtems.org
>> > <mailto:chrisj at rtems.org>> wrote:
>> >
>> >     On 18/11/2022 2:39 am, Kinsey Moore wrote:
>> >      > I recently added FDT support to the AArch64 ZynqMP BSPs to
>> >     support an optional
>> >      > management console and managing ethernet parameters for LibBSD.
>> >     Use of the
>> >      > rtems_fdt_* functions implies use of malloc which adds 4 bytes in
>> >     the TLS space.
>> >      > The sp01 test uses rtems_task_construct and specifies a maximum
>> >     TLS size of 0
>> >      > bytes which causes a failure which the non-zero TLS size is
>> >     checked against the
>> >      > maximum TLS size of 0.
>> >
>> >     Does this mean there exists a requirement a BSPs cannot internally
>> >     use the heap?
>> >
>> >
>> > That appears to be the case, at least practically. It works fine, but
>> it
>> > causes a test failure...
>>
>> You can use the heap during system initialization. However, you should
>> avoid dependencies on errno, so instead of using malloc()/calloc() use
>> rtems_malloc()/rtems_calloc(). Independent of this, if the BSP
>> initialization can easily avoid the heap, then it should not use the heap.
>>
>> >
>> >
>> >     Maybe the test needs to be adjusted?
>> >
>> >
>> > That's part of why I sent this to the list. I was unsure whether it was
>> > allowed or whether the test had bad assumptions baked into it.
>>
>> The tests check specific aspects of the thread-local storage support and
>> this works only if the BSP does not depend on TLS objects such as errno.
>>
>> This affects several other tests as well, so I guess my solution here is
> either to alter the rtems_fdt_ wrappers to avoid dependencies on TLS or
> proceed with the existing patch that uses the non-wrapped FDT functions.
>

I agree with Sebastian that fixing the bsp is right.

But also rtems_ fdt methods should be changed to use rtems_malloc. That
would leave those methods useful. They are broken now for many intended use
cases.


> Thanks!
>
> Kinsey
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