Deprecation/removal of nios2 target support

[Sandra Loosemore]

On 4/18/24 10:06, Jeff Law wrote:
> 
> ACK.  Just one more note to the wider audience.  I looked at QEMU's user 
> mode support for nios2 on/off over the last couple years.  It never 
> seemed to work well enough be able to run the GCC testsuite reliably.

I looked at the problems with the nios2 user-mode support in QEMU in 
some detail a few years ago.  It looked like the problem was that it had 
copied the target syscall data structures from GLIBC and wasn't 
accounting for 32-bit target/64-bit host differences -- this 
particularly affected signal handling.  I'm pretty sure we asked Intel 
if they wanted this fixed and they were not interested in pursuing that. 
  The end result is that user-mode QEMU is not very useful for GLIBC or 
GDB testing.

> As a result, my tester builds nios2 and will run the testsuite, but all 
> the execution tests are only built, they're not actually run.  It's been 
> fairly stable, but its not doing in-depth testing.

Yes, as I noted in my previous message, there is nothing seriously wrong 
with the nios2 GCC port at present; it just seems kind of pointless to 
invest time in continuing to maintain it as a hobby when the 
architecture is dead.  I think legacy customers generally would prefer 
to keep using the toolchains previously distributed by Altera/Intel or 
Mentor/Siemens instead of trying to build a new bleeding-edge toolchain 
from scratch, too.

-Sandra