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Consensus summary around changing GLIBC PPC64 LE ABI default to 2.17
- From: "Carlos O'Donell" <carlos at redhat dot com>
- To: Adam Conrad <adconrad at 0c3 dot net>, Andreas Jaeger <aj at suse dot com>, Steven Munroe <sjmunroe at us dot ibm dot com>, Adhemerval Zanella <azanella at linux dot vnet dot ibm dot com>, "Joseph S. Myers" <joseph at codesourcery dot com>, Jeff Law <law at redhat dot com>, Roland McGrath <roland at hack dot frob dot com>, Andreas Schwab <schwab at suse dot de>, "H.J. Lu" <hjl dot tools at gmail dot com>, Brooks Moses <bmoses at google dot com>, GNU C Library <libc-alpha at sourceware dot org>
- Date: Fri, 31 Jan 2014 18:57:21 -0500
- Subject: Consensus summary around changing GLIBC PPC64 LE ABI default to 2.17
- Authentication-results: sourceware.org; auth=none
- References: <52EC34E1 dot 7040008 at redhat dot com>
The decision to switch the ABI default to 2.17 has been made by IBM here:
https://sourceware.org/ml/libc-alpha/2014-01/msg00799.html
This email is to record final consensus around this issue.
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Consensus summary around changing GLIBC PPC64 LE ABI default to 2.17
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Please correct me if I'm wrong.
IBM (Steven Munroe) - Yay.
Red Hat (Carlos O'Donell) - Yay.
- Sustained opposition to leaving ABI baseline at GLIBC_2.18.
- Provided patches to help others rebuild during ABI change.
SUSE (Andreas Jaeger) - Nay.
- Needs to rebuild distribution with new ABI.
Canonical (Adam Conrad) - Nay.
- Needs to rebuild distribution with new ABI.
Joseph Myers - No sustained opposition
- Considers use of 2.19 ABI the only sensible policy.
- Considers symbol backports easy. Example given Nios II.
Roland McGrath - No sustained opposition.
- Considers use of 2.19 ABI the only sensible policy.
H.J. Lu - No sustained opposition
- Considers symbol backports easy. Example given x32.
Brooks Moses - No sustained opposition.
The goal of the discussions were to reach some consensus regarding
the PPC64 LE ABI changes to support 2.17-based distributions.
The three main technical answers to the question of "Which ABI?" are:
(a) Distros rebase glibc on 2.19 and rebuild with GLIBC_2.19.
- Red Hat is unable to do this given their constraints. The assumption
is that it's also out of the picture for SUSE and Canonical which
have 2.18-based distributions.
(b) Stay on 2.1[78] sources using GLIBC_2.1[89] default ABI and backport
all 2.1[89] symbols to produce a 2.1[78]-based release whose ABI
is identical to the GLIBC_2.1[89] ABI released upstream.
- Despite statements by several developers that this is easy, no major
enterprise distribution has been released with a glibc patched like this.
There may be additional risk.
- It is expected that neither SUSE nor Canonical want to try have a hybrid
symbol release either. Thus setting the ABI baseline to GLIBC_2.19
places them in the same position it places other 2.17-based distributions
with GLIBC_2.18 as the default ABI.
(c) Move the ABI baseline to GLIBC_2.17.
- This is what Red Hat and IBM propose to support 2.17-based and newer
distributions in the PPC64 LE ecosystem.
After input from all parties the decision has been made by the machine
maintainer IBM to choose (c).
Cheers,
Carlos.