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Re: The time(2) man page conflicts with glibc
- From: Zack Weinberg <zackw at panix dot com>
- To: Andreas Schwab <schwab at suse dot de>, GNU C Library <libc-alpha at sourceware dot org>
- Date: Tue, 15 Dec 2015 09:46:31 -0500
- Subject: Re: The time(2) man page conflicts with glibc
- Authentication-results: sourceware.org; auth=none
- References: <CAMe9rOoJLk8VzyJKmkOvbmBxhCj4mVA2huYtHJsdxpatbkgJ1g at mail dot gmail dot com> <CAKCAbMj-X+wLKX3=MDm9z3L9zyikemxCNggu2bfw6=o6K5PGgg at mail dot gmail dot com> <mvm7fkf941w dot fsf at hawking dot suse dot de>
On Tue, Dec 15, 2015 at 9:31 AM, Andreas Schwab <schwab@suse.de> wrote:
> Zack Weinberg <zackw@panix.com> writes:
>
>> I did. The *actual system call* does indeed return -EFAULT when
>> memory is invalid, which will be observed as 0xfffffffffffffff2 in the
>> return value. However, the *vDSO shortcut* (which does not trap into
>> the kernel) will just segfault the application. This is an observable
>> ABI difference between statically and dynamically linked binaries.
>
> Undefined behaviour can change any time in any way and is not part of
> the ABI.
I should have said "observable behavior difference".
zw