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Re: PATCH: Check GLIBC_IFUNC to enable/disable ifunc features
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Siddhesh Poyarekar <siddhesh at sourceware dot org>
- Cc: "Carlos O'Donell" <carlos at redhat dot com>, GNU C Library <libc-alpha at sourceware dot org>
- Date: Thu, 30 Jun 2016 04:34:53 -0700
- Subject: Re: PATCH: Check GLIBC_IFUNC to enable/disable ifunc features
- Authentication-results: sourceware.org; auth=none
- References: <CAMe9rOq1+_rMbs1mt3=Md=Wx=7ZxUbD+BhOx-qrO5TBRBrRLww at mail dot gmail dot com> <20160630030947 dot GD3824 at devel dot intra dot reserved-bit dot com> <CAMe9rOrd+DEP1POnXaUaOrCaGqMmrftJbR_6ydFCXQeWueWmag at mail dot gmail dot com> <20160630034351 dot GE3824 at devel dot intra dot reserved-bit dot com>
On Wed, Jun 29, 2016 at 8:44 PM, Siddhesh Poyarekar
<siddhesh@sourceware.org> wrote:
> On Wed, Jun 29, 2016 at 08:22:15PM -0700, H.J. Lu wrote:
>> GLIBC_IFUNC must be processed after init_cpu_features is called and before
>> any relocation is performed. Otherwise, IFUNC won't work correctly. Can your
>> tunable scheme support it?
>
> Yes, one of the desired use cases for tunables has been to control
> IFUNC behaviour.
Another concern is we only need to check one GLIBC_IFUNC and
done. With GLIBC_IFUNC_X86_XXX, it becomes open ended. I
really want to avoid it.
--
H.J.