RFR: 8324834: Use _LARGE_FILES on AIX

[Magnus Ihse Bursie]

On Mon, 29 Jan 2024 13:51:29 GMT, Joachim Kern <jkern at openjdk.org> wrote:

>> In the same spirit as [JDK-8318696](https://bugs.openjdk.org/browse/JDK-8318696), we should adapt the AIX-specific code in hotspot so it uses the well-defined posix `<foo>` functions, instead of `<foo>64`. By setting the define _LARGE_FILES, this will make `<foo>` behave as `<foo>64`, just as _FILE_OFFSET_BITS=64 does on gcc. (Reference: https://www.ibm.com/docs/en/aix/7.1?topic=volumes-writing-programs-that-access-large-files)
>> 
>> In theory, it should not even be necessary to set this, since we only compile for 64-bit AIX platforms, and this is only relevant on 32-bit platforms. But let's add the define anyway, for good measure. It shows at least that we have thought about the matter. :-)
>> 
>> I have not been able to test this on AIX. I hope someone with AIX access can take this for a spin.
>> 
>> The reason I'm doing this is for [JDK-8324539](https://bugs.openjdk.org/browse/JDK-8324539). After both these bugs are fixed, there will be no more `<foo>64` function calls in the code base.
>
> I have to emphasize, that even when exclusively compiling for 64-bit AIX platforms, the  `<foo>` functions do not support large files. Only the `<foo>64` functions do support large files.
> For large file support you can either use the `<foo>64` functions and the `<struct>64` structures explicitly or by compiling all sources with the -D_LARGE_FILES flag which just leads to a redefining of all `<foo>` functions and `<struct>` structures as `<foo>64` functions and `<struct>64` structures.

@JoKern65 Thanks for the information; I did not know that. But the only change it makes is it turns the `-D_LARGE_FILES` from "nice" to "essential" -- the patch remains the same.

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PR Comment: https://git.openjdk.org/jdk/pull/17611#issuecomment-1916727453