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Re: [PATCH] Add new script add-abilist.py
- From: "Carlos O'Donell" <carlos at redhat dot com>
- To: Joseph Myers <joseph at codesourcery dot com>
- Cc: Roland McGrath <roland at hack dot frob dot com>, Florian Weimer <fweimer at redhat dot com>, libc-alpha at sourceware dot org
- Date: Fri, 06 Mar 2015 14:03:23 -0500
- Subject: Re: [PATCH] Add new script add-abilist.py
- Authentication-results: sourceware.org; auth=none
- References: <20150302080300 dot B464D4242A0BE at oldenburg dot str dot redhat dot com> <20150302201942 dot AC9532C39F1 at topped-with-meat dot com> <54F4CCCC dot 3070500 at redhat dot com> <20150302205928 dot C13FE2C3A08 at topped-with-meat dot com> <54F4CFCE dot 1020700 at redhat dot com> <54F8AED7 dot 2090109 at redhat dot com> <54F8C425 dot 8070501 at redhat dot com> <54F8CD76 dot 8030704 at redhat dot com> <20150305220313 dot A70CC2C3AB9 at topped-with-meat dot com> <54F8D36C dot 9020007 at redhat dot com> <alpine dot DEB dot 2 dot 10 dot 1503061837530 dot 24477 at digraph dot polyomino dot org dot uk>
On 03/06/2015 01:48 PM, Joseph Myers wrote:
> On Thu, 5 Mar 2015, Carlos O'Donell wrote:
>
>> (b) A trybot that you can use to scrape the results of `make update-abi`
>> which gives you perfect confidence that things are working as
>> expected.
>
> One important case is that a bug in the change means that some
> architecture doesn't actually get the new function, and so if you don't
> update that architecture's ABI baselines in a way corresponding to other
> architectures, a make update-abi on that architecture results in no
> changes at all, and make check-abi does not fail there, and the new
> function is quietly missing there.
Oh, that's a really good point, and a very good reason for accepting
a script that simply updates all baselines.
> Manually updating ABIs, possibly helped by a script, to reflect the intent
> that the new function appears on all architectures, is one way to help
> avoid such bugs (by making them result in visible check-abi failures
> unless you accidentally miss updating the baselines for exactly the same
> architectures as miss the new functions). Of course we should *also* add
> testcases that verify the new function calls at least link (even if no
> runtime test is possible without e.g. a new Linux kernel or running with
> privileges) - as that would also detect such problems.
Agreed.
> (fallocate64 being added in 2.10 on 64-bit architectures but 2.11 on
> 32-bit architectures
> <https://sourceware.org/ml/libc-hacker/2009-05/msg00003.html> is the
> prototypical example of a bug that could have been found this way.)
Yes.
Cheers,
Carlos.