Re: [PATCH] sys/tree.h: Removed

[Joel Sherrill <joel@rtems.org>]

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On Thu, Jun 20, 2024 at 4:13 AM Sebastian Huber <
sebastian.huber@embedded-brains.de> wrote:

> On 18.06.24 22:25, Joel Sherrill wrote:
> > This file was from a specific older FreeBSD version. There have been
> > multiple changes to this file with FreeBSD 14 including breaking
> > changes to the file.
>
> What kind of breaking changes did you observe in the FreeBSD 14 version
> of <sys/tree.h>? I see no breaking API changes. FreeBSD changed the
> implementation to use rank-balanced trees instead of red-black trees,
> but this should not have resulted in API breaks (the ABI changed though).
>

This creates a conflict between the libc and rtems-libbsd versions. When
both are installed, the header installed by libbsd results in different code
than the version RTEMS was compiled with.

Using this internally in RTEMS, we opened ourselves to external changes
impacting the score implementation of rbtree.  This leaves us
open to external changes having an impact on performance.
We should take on the preferred implementation inside the score of
RTEMS so we have control. We will end up having to do something
with the file name and name space.

This actually violated a core development principle for RTEMS and
we should have spotted this long ago. Everything in the score and
"bottom" of RTEMS should not depend on libc.

We need to control the implementation used internal to RTEMS.
Realizing that it was not up date in newlib just triggered the realization
that we should not have been using it.

--joel


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