On 10/12/2016 02:02 AM, Jakub Jelinek wrote:
On Wed, Oct 12, 2016 at 09:52:04AM +0200, Florian Weimer wrote:
dropping the alignment means that the padding before the lock member
vanishes. Consequently, we have just created a silent ABI change in
application code, which is a big no-no.
Sure, it would be an ABI change, but how many users would it affect?
If the issue is strictly limited to 32 bit hpux, then do we really care?
Can we just deprecate that platform and thus make the issue go away?
Since this is PA-RISC, which is essentially dead (neither HPE nor Debian
ship it anymore), I stand by my suggestion to bump the fundamental alignment
Or just drop support for a dead arch?
instead. Sure, it is a bit inefficient, but this will only affect PA-RISC
users. It does not even cause work for PA-RISC porters. Conversely, if we
work on this to come up with a different fix, many more people will be
affected (because they don't get all the nice things we could work on
instead), and we may need to maintain a special GCC kludge for the
alternative solution, impacting GCC developers in particular.
But sure, bumping malloc alignment is probably easiest. And people who want
performance have better options than to stay on 32-bit PA-RISC anyway.
It's really hard to make an argument to do anything other than deprecate
that platform. Given John's ongoing involvement it's much harder to
deprecate 64bit linux (and consequently 64bit hpux).