Deprecation/removal of nios2 target support

[Thomas Huth]

On 18/04/2024 05.27, Sandra Loosemore wrote:
> Tomorrow I plan to push patches to mark the nios2 target as obsolete in GCC 14.
> 
> Background: Intel has EOL'ed the Nios II processor IP and is now directing 
> their FPGA customers to a RISC-V platform instead.
> 
> https://www.intel.com/content/www/us/en/content-details/781327/intel-is-discontinuing-ip-ordering-codes-listed-in-pdn2312-for-nios-ii-ip.html
> 
> The Nios II hardware on loan from Intel that we were using for testing at 
> Mentor Graphics/Siemens was returned around the first of the year. For some 
> time we had been using QEMU to test the nios2-elf target, but we never had a 
> QEMU test harness set up that would boot the Linux kernel, and user-mode 
> QEMU on this target is too buggy/unmaintained to use for primary testing.  
> So the current situation is that none of the listed maintainers for any of 
> the GNU toolchain components have access to a fully working test 
> configuration any more, we have all moved on to new jobs and different 
> projects, Intel has also moved on to a different platform, and our former 
> contacts on Intel's Nios II team have moved on as well.  It seems like it's 
> time to pull the plug.
> 
> Therefore I'd like to mark Nios II as obsolete in GCC 14 now, and remove 
> support from all toolchain components after the release is made.  I'm not 
> sure there is an established process for obsoleting/removing support in 
> other components; besides binutils, GDB, and GLIBC, there's QEMU, 
> newlib/libgloss, and the Linux kernel.  But, we need to get the ball rolling 
> somewhere.

Thanks for the heads-up, Sandra! FWIW: QEMU already marked the nios2 target 
as deprecated, too, and plans to remove it in version 9.1 (in autumn this year).

  Thomas