Re: Discussion about why GNU/Linux system upgrades cause old programs to break

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  > > 2. "SIGSTKSZ on GNU/Linux is not a constant expression any more": does
  > > that mean (1) SIGSTKSZ _may_ not be a constant, if the architecture in
  > > use requires varying sizes of stacks, or (2) SIGSTKSZ is _never_ a
  > > constant, on any architecture, whether it actually can vary or not?

  > It seems that it was made non-constant for all arches, even those that
  > won't vary in the future.

  > > 3. What is the latest GCC definition of SIGSTKSZ on the x86_64 architecture?

  > With _DYNAMIC_STACK_SIZE_SOURCE (and, thus, also with _GNU_SOURCE):

  >   ~$ gcc -E -dM -include signal.h -x c /dev/null -o - -D_DYNAMIC_STACK_SIZE_SOURCE | grep ' SIGSTKSZ'
  >   #define SIGSTKSZ sysconf (_SC_SIGSTKSZ)
  >   #define MINSIGSTKSZ SIGSTKSZ

I see the issue now.  Thanks for explaining it.

SIGSTKSZ is a very obscure feature, so I think it will be rare that
old user programs refer to it at all.  But...

    I presume it wasn't done in
  > this case because SIGSTKSZ has fairly few users (only 4.7K instances
  > over all of Debian, among which is Emacs; note that not all of those
  > uses will break),

I'm surprised -- 5000 uses seems surprisingly many to me.  Are most of
those uses in the Linux sources?  It would be used a lot there.

For curiosity, can you show us the list of programs in Debian that
refer to SIGSTKSZ?  I wonder how many ordinary user programs refer to
it.

-- 
Dr Richard Stallman (https://stallman.org)
Chief GNUisance of the GNU Project (https://gnu.org)
Founder, Free Software Foundation (https://fsf.org)
Internet Hall-of-Famer (https://internethalloffame.org)