libdl support for base image TLS variables

[Joel Sherrill]

On Wed, Aug 16, 2023, 8:30 PM Chris Johns <chrisj at rtems.org> wrote:

> On 17/8/2023 6:34 am, Gedare Bloom wrote:
> > On Mon, Aug 14, 2023 at 10:05 PM <chrisj at rtems.org> wrote:
> >>
> >> These patches add support to rtems.git and rtems-tools.git to
> >> provide access to TLS variables in the base from loaded code.
> >> The changes contain the ground work to resolving #4920 which is
> >> a blocker for the release of 6.
> >>
> >> This change is required due to the regression in libdl due to the
> >> change in newlib to use TLS variables for reneterant data.
> >>
> >> The rtems.git patch can be applied before the rtems-tools.git
> >> patch. If the tools are updated and the libdl code is not present
> >> the tests fail with linker errors. If the tools change is
> >> not present the test will link but it will continue to fail.
> >>
> >> The currently supported archs that build are:
> >>
> >>  - aarch64
> >>  - arm
> >>  - powerpc
> >>  - sparc
> >>
> >> The follow are to be completed and do not build:
> >>
> >>  - bfin
> >>  - i386
> >>  - lm32
> >>  - m68k
> >>  - mips
> >>  - moxie
> >>  - riscv
> >>  - v850
> >>
> >> We need to add support for these architectures if they support TLS.
> >>
> > We are deprecating v850. It might be worth considering whether some of
> > these other architectures should also be deprecated, especially if no
> > one is able/willing to add TLS for them.
>
> From Joel's comments on #4920 some have TLS but the newlib support has not
> been
> updated. Newlib TLS support for reent is a nice and welcomed feature but
> not
> having newlib TLS support means the arch is performing as before.
>

Is TLS off on some architectures?

Is that a column missing in the table I added?


> The other TSL issue is gdb is broken. If you attempt to print errno you
> will be
> told TLS is not supported by gdb for this OS.
>

That seems harder.

>
> A review of archs should happen before 6 is released so we can indicate
> which we
> will remove for 7. What have we indicated is to be removed in 7?
>

 SH, v850, and sparc64.


> Chris
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