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Re: RFC: Add ___tls_get_addr
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Florian Weimer <fweimer at redhat dot com>, "x86-64-abi at googlegroups dot com" <x86-64-abi at googlegroups dot com>, GCC Development <gcc at gcc dot gnu dot org>, GNU C Library <libc-alpha at sourceware dot org>
- Date: Wed, 5 Jul 2017 09:30:14 -0700
- Subject: Re: RFC: Add ___tls_get_addr
- Authentication-results: sourceware.org; auth=none
- References: <CAMe9rOrYdAh6kJUUTdyzWdwfhEWVuiHJVs5xhp4pVbeB6hEM1w@mail.gmail.com> <firstname.lastname@example.org> <CAMe9rOpPz=Sh5vnSzoKQQbaRCoqEusMRa1EUZnWc-sH_op7CnA@mail.gmail.com> <email@example.com> <CAMe9rOriEnzjnDkwjxDM6mEoeZXHVy+NMfwjZMZm1y5MtncZ+A@mail.gmail.com> <firstname.lastname@example.org>
On Wed, Jul 5, 2017 at 9:27 AM, Florian Weimer <email@example.com> wrote:
> On 07/05/2017 06:21 PM, H.J. Lu wrote:
>> On Wed, Jul 5, 2017 at 9:18 AM, Florian Weimer <firstname.lastname@example.org> wrote:
>>> On 07/05/2017 06:17 PM, H.J. Lu wrote:
>>>> On Wed, Jul 5, 2017 at 9:09 AM, Florian Weimer <email@example.com> wrote:
>>>>> On 07/05/2017 05:38 PM, H.J. Lu wrote:
>>>>>> We are considering to add an alternative interface, ___tls_get_addr, to
>>>>>> glibc, which doesn't realign stack. Compilers, which properly align stack
>>>>>> for TLS, call generate call to ___tls_get_addr, instead of __tls_get_addr,
>>>>>> if ___tls_get_addr is available.
>>>>> Why can't we add a new symbol version instead? Those who recompile or
>>>>> relink their applications would have to use fixed compilers.
>>>> When GCC 4.8 is used to compile packages under the new glibc, the new
>>>> version of ___tls_get_addr will be used. But the alignment will be wrong.
>>> GCC 4.8 is out of support. Do not use it, or use it along with a
>>> matching glibc.
>> We do support old GCCs to be used with the new glibc, just not to support
>> them to build glibc.
> There is no promise that we will work around compiler bugs in old GCCs,
We are supporting older GCCs as much as we can.