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Re: [PATCH] i386: Increase MALLOC_ALIGNMENT to 16 [BZ #21120]
On 06/29/2017 02:43 PM, H.J. Lu wrote:
> On Thu, Jun 29, 2017 at 11:11 AM, Carlos O'Donell <carlos@redhat.com> wrote:
>> On 06/29/2017 02:06 PM, H.J. Lu wrote:
>>> On Thu, Jun 29, 2017 at 10:55 AM, Carlos O'Donell <carlos@redhat.com> wrote:
>>>> On 06/29/2017 01:30 PM, H.J. Lu wrote:
>>>>> GCC 7 changed the definition of max_align_t on i386:
>>>>>
>>>>> https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=9b5c49ef97e63cc63f1ffa13baf771368105ebe2
>>>>>
>>>>> As a result, glibc malloc no longer returns memory blocks which are as
>>>>> aligned as max_align_t requires.
>>>>>
>>>>> This causes malloc/tst-malloc-thread-fail to fail with an error like this
>>>>> one:
>>>>>
>>>>> error: allocation function 0, size 144 not aligned to 16
>>>>>
>>>>> This patch increases the malloc alignment to 16 for i386.
>>>>>
>>>>> Tested on i386 with GCC 7 and on x86-64. OK for master?
>>>>>
>>>>> H.J.
>>>>> ---
>>>>> [BZ #21120]
>>>>> * sysdeps/generic/malloc-alignment.h: New file.
>>>>> * sysdeps/i386/malloc-alignment.h: Likewise.
>>>>> * sysdeps/generic/malloc-machine.h: Include <malloc-alignment.h>.
>>>>
>>>> Please use malloc-machine.h which was the previous header that provided
>>>> machine-dependent malloc definitions. That way we remain consistent across
>>>> releases and make it easier to backport such changes without adding a new
>>>> header.
>>>
>>> It won't work too well for Hurd since we have
>>>
>>> ./sysdeps/generic/malloc-machine.h
>>> ./sysdeps/mach/hurd/malloc-machine.h
>>> ./sysdeps/nptl/malloc-machine.h
>>>
>>> What will Hurd/i386 get? malloc-alignment.h handles it automatically.
>>
>> If your patch made Hurd/i386 use MALLOC_ALIGNMENT of 16 then a new patch
>> using malloc-machine.h would set MALLOC_ALIGNMENT to 16 in
>> systeps/mach/hurd/malloc-machine.h?
>>
>
> This assumes that mach/hurd == i386. Also I don't like define
> MALLOC_ALIGNMENT to 16 for i386 in 2 different places.
> Since
>
> ./sysdeps/generic/malloc-machine.h
> ./sysdeps/mach/hurd/malloc-machine.h
> ./sysdeps/nptl/malloc-machine.h
>
> malloc-machine.h is not pure processor specific. It is also OS
> specific. I prefer to define MALLOC_ALIGNMENT to 16 for i386
> in a processor specific header file.
Add a sysdeps/mach/hurd/i386, which is an os/machine directory.
Similarly for i386?
--
Cheers,
Carlos.