Distributions still suffering from s390 ABI change problems.

[Aurelien Jarno]

On Tue, Jul 15, 2014 at 01:00:09AM -0400, Rich Felker wrote:
> On Mon, Jul 14, 2014 at 12:50:34PM -0400, Carlos O'Donell wrote:
> > On 07/14/2014 03:25 AM, David Miller wrote:
> > > From: Aurelien Jarno <aurelien@aurel32.net>
> > > Date: Mon, 14 Jul 2014 09:22:28 +0200
> > > 
> > >> We can continue handling this ABI change by rebuilding all packages
> > >> dependind on libpng, but I am afraid that embedding a jmp_buf in a
> > >> structure is not that uncommon and that we are going to discover
> > >> more affected packages.
> > > 
> > > This is a really serious mess.
> > 
> > There was no other way around this, and our tooling sucks for detecting
> > mixed ABI usage and telling users how to fix it.
> 
> Yes there was. No matter how much state setjmp needs to store, there
> is always a way to avoid ABI breakage as long as jmp_buf is at least
> the size of a pointer:
> 
> #define setjmp(jb) __new_setjmp(jb, alloca(__get_real_jb_size()))
> 
> Then the jmp_buf need only store a pointer to the caller-provided
> register-storage space.

This would work if jmp_buf was an opaque structure. It is not the case
and we can imagine code accessing its content. In that case it will
still break.

-- 
Aurelien Jarno                          GPG: 4096R/1DDD8C9B
aurelien@aurel32.net                 http://www.aurel32.net