This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
Re: [PATCH] change GLIBC PPC64/ELF2 ABI default to 2.17
- From: Jeff Law <law at redhat dot com>
- To: munroe at us dot ibm dot com, sjmunroe at us dot ibm dot com, libc-alpha at sourceware dot org
- Cc: Adhemerval Zanella <azanella at linux dot vnet dot ibm dot com>, "Carlos O'Donell" <carlos at redhat dot com>, Andreas Schwab <schwab at linux-m68k dot org>, Roland McGrath <roland at hack dot frob dot com>, Adam Conrad <adconrad at 0c3 dot net>
- Date: Fri, 31 Jan 2014 00:02:50 -0700
- Subject: Re: [PATCH] change GLIBC PPC64/ELF2 ABI default to 2.17
- Authentication-results: sourceware.org; auth=none
- References: <1391008726 dot 16702 dot 105 dot camel at spokane1 dot rchland dot ibm dot com> <1391134218 dot 8757 dot 120 dot camel at oc8268013063 dot ibm dot com>
On 01/30/14 19:10, Steven Munroe wrote:
So we have had a spirited debate and expressed our issues in a
forthright manner. Clearly this is frustrating to many of you but I also
see a developing consensus.
* GLIBC-2.19 is the first official release for the new PPC64LE
ELF2 ABI.
* GLIBC-2.19 establishes the basis for compatibility for the ABI.
* GLIBC-2.19 will establish the "default or minimum" version for
this ABI.
* Once GLIBC-2.19 is released the "default" version should not
change (ever!).
* Any back-ports of this ABI to older versions of GLIBC are
responsible to maintaining forward compatibility to 2.19.
* No back-ports will be supported earlier then "default" set in
the official GLIBC-2.19 release.
Does anyone disagree with the statements above?
Not me. I agree with everything stated above.
Jeff and Carlos are looking at means to reduce the reset from a "full
bootstrap and rebuild the world" to just a "automated rebuilt the
world". All of us in active development are concerned about this and I
hope they will share their solution.
Anything we come up with will certainly be shared. Ideally what we're
looking at would allow a system with both old and new binaries to work
for a period of time so that the transition is a rebuild, not a
re-bootstrap. I repeat, it'll be a hack -- nothing that could ever be
upstreamed, just something to reduce the pain of the change if it's
installed. Once the rebuild is complete, the hack should be removed,
possibly requiring another rebuild/reinstall of just glibc to do so.
And just to be clear, Carlos is doing the heavy lifting here, I'm mostly
throwing out ideas. His knowledge of glibc exceeds mine by orders of
magnitude.
1) Changing the default to 2.19 would force a reset for everyone evolved
in the PPC64LE ELf2 ABI today. It would also exclude (for some long
period of time) some of the current distributors.
2) Leaving the default at 2.18 would reduce (but not eliminate) the risk
for some distributors (2.18 back-ports) but still excludes others (again
for some long period of time).
3) Changing the default to 2.17 would also force a reset for everyone
evolved in the PPC64LE ELf2 ABI today. It is also the most inclusive and
in the long run provides a larger and more inviting ecosystem for the
new platform. It still established definite boundary moving forward.
As I'm sure you know, I favor #3.
jeff