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Re: [PATCHv3] powerpc: ABI change - add HWCAP/HWCAP2/platform info to TCB
- From: Carlos Eduardo Seo <cseo at linux dot vnet dot ibm dot com>
- To: "Carlos O'Donell" <carlos at redhat dot com>
- Cc: munroesj at linux dot vnet dot ibm dot com, Peter Bergner <bergner at vnet dot ibm dot com>, Roland McGrath <roland at hack dot frob dot com>, Joseph Myers <joseph at codesourcery dot com>, GNU C Library <libc-alpha at sourceware dot org>, Tulio Machado <tuliom at linux dot vnet dot ibm dot com>, "Steven J. Munroe" <sjmunroe at us dot ibm dot com>
- Date: Mon, 12 Oct 2015 21:13:32 -0300
- Subject: Re: [PATCHv3] powerpc: ABI change - add HWCAP/HWCAP2/platform info to TCB
- Authentication-results: sourceware.org; auth=none
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Good. Iâll submit a new version of the patch with the changes you suggested after my other patch that adds AT_PLATFORM to _dl_aux_init () gets accepted.
Thanks,
--
Carlos Eduardo Seo
Software Engineer - Linux on Power Toolchain
cseo@linux.vnet.ibm.com
> On Oct 9, 2015, at 5:17 PM, Carlos O'Donell <carlos@redhat.com> wrote:
>
> On 10/09/2015 04:14 PM, Carlos Eduardo Seo wrote:
>>
>>> On Oct 9, 2015, at 4:57 PM, Carlos O'Donell <carlos@redhat.com> wrote:
>>>
>>> That's up to you to prove by looking at the places where you've added
>>> the initialization sequences. My guess is that you're probably good because
>>> all of these sequences are run before main and before any thread is created
>>> and before any CTORs are run. I'd like you to verify that though.
>>>
>>> In which case the next steps are:
>>> - Remove ppc.h functions.
>>> - Verify all init is done before CTORs
>>> - Post smaller v4 patch.
>>
>>
>> I believe weâre good because the data we need in the TCB must be initialized before the first call to TLS_INIT_TP. That means:
>>
>> - in _dl_sysdep_start for the dynamic linking case
>> - in __libc_start_main for the static linking case
>>
>> This should guarantee that the TCB is initialized with the data we need before main, or any other thread, or CTORs are run.
>
> Looks good to me.
>
> The worst thing that can happen is this turns out to be
> wrong and we just move the initialization earlier and
> the distributions have to patch and update. No ABI impact.
>
> Cheers,
> Carlos.