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Re: [PATCH 1/2] Add --with-ilp32-large-off_t


On Fri, Jul 6, 2012 at 7:54 AM, Andreas Jaeger <aj@suse.com> wrote:
> On 07/06/2012 04:32 PM, H.J. Lu wrote:
>>
>> On Fri, Jul 6, 2012 at 7:15 AM, Andreas Jaeger <aj@suse.com> wrote:
>>>
>>> On 07/06/2012 04:05 PM, H.J. Lu wrote:
>>>>
>>>>
>>>> Hi,
>>>>
>>>> On x86-64, ILP32 with large off_t (64-bit) can be either -mx32 or -m32
>>>> with "-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64".  This patch adds
>>>> a configure time option to choose which one to use for ILP32_OFFBIG.
>>>> Any comments?
>>>
>>>
>>>
>>> I'm not sure what you're doing, this sounds really wrong to me and I
>>> smell
>>> an ABI breakage. So, please help me to understand the problem you're
>>> trying
>>> to solve.
>>>
>>> Could you show a short example program that has a problem and explain the
>>> problem a bit more?
>>>
>>
>> See:
>>
>> http://sourceware.org/ml/libc-alpha/2012-05/msg02093.html
>
>
>
> Thanks, I see the problem. We surely should not make this the default since
> I expect slow adoption of the new ABI - and most people won't have a full
> development environment for it but will have on for x86 (-m32).

By default, nothing is changed, except for x32 glibc, which will use -mx32
for ILP32_OFFBIG.

> Looking at the rather large diff together with the additional regenerated
> file, I wonder whether we really need to make this change now or wait until
> x32 has seen better adoption.

Unless you configure glibc with --with-ilp32-large-off_t=mx32,
there should be no changes for -m64 nor -m32.

> Btw. you say Patch 1 of 2 - where's the second one?

Here is the second patch:

http://sourceware.org/git/?p=glibc.git;a=patch;h=4c43d953820a1e0562416d6f3a313571ecd59eda

I will submit it, pending on status of the first patch.

> Before this patch goes in, the configure option needs better explanation
> about what it does and what the arguments are. It is not self-explainable at
> all right now,
>

Sure.

Thanks.

-- 
H.J.


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