RFR [XS]: 8208744: remove unneeded -DUSE_MMAP settings for JDK native libs builds -was : RE: unneeded -DUSE_MMAP in JDK native libs builds

[David Holmes]

Looks fine to me.

Thanks,
David

On 3/08/2018 4:13 PM, Baesken, Matthias wrote:
> Hello,  I can confirm what David said .
> Additionally I grepped through /usr/include on my Linux machine and did not  find any  USE_MMAP occurences.
> 
> I created this  webrev +  bug :
> 
> http://cr.openjdk.java.net/~mbaesken/webrevs/8208744/
> 
> https://bugs.openjdk.java.net/browse/JDK-8208744
> 
> 
> Please review !
> 
> 
> Thanks, Matthias
> 
> 
>> -----Original Message-----
>> From: David Holmes <david.holmes at oracle.com>
>> Sent: Freitag, 3. August 2018 02:56
>> To: Magnus Ihse Bursie <magnus.ihse.bursie at oracle.com>; Baesken,
>> Matthias <matthias.baesken at sap.com>
>> Cc: build-dev at openjdk.java.net
>> Subject: Re: unneeded -DUSE_MMAP in JDK native libs builds
>>
>> On 3/08/2018 3:44 AM, Magnus Ihse Bursie wrote:
>>>
>>>> 2 aug. 2018 kl. 05:33 skrev Baesken, Matthias
>> <matthias.baesken at sap.com>:
>>>>
>>>> Hello I noticed that   -DUSE_MMAP  is set for these  JDK native libs, but I
>> cannot find it in the code   (for libzip it is different there the flag shows up in
>> the code too ) :
>>>
>>> I've always assumed that this was used to control the behavior in some
>> imported header files. Have you verified that this is not the case?
>>
>> It is only used in
>>
>> ./java.base/share/native/libzip/zip_util.c
>> ./java.base/share/native/libzip/zip_util.h
>>
>> and the header itself is only included in the .c file. So unless this
>> source file is used for the other libraries (which I don't see) then we
>> don't need -DUSE_MMAP when building them.
>>
>> AFAIKS the use of this for BUILD_LIBDT_SOCKET and BUILD_LIBDT_SHMEM
>> dates back to the build-infra changes in JDK 8.
>>
>> http://hg.openjdk.java.net/jdk8/jdk8/jdk/rev/9d3d01aca52c
>>
>> But I can't see why it was introduced there.
>>
>> In JDK 7 it's only applied to the zip library.
>>
>> Cheers,
>> David
>> -----
>>
>>>
>>> /Magnus
>>>
>>>>
>>>> Lib-jdk.jdi.gmk  :
>>>>
>>>> 32  $(eval $(call SetupJdkLibrary, BUILD_LIBDT_SHMEM, \
>>>> ......
>>>> 35 CFLAGS := $(CFLAGS_JDKLIB) -DUSE_MMAP, \
>>>>
>>>>
>>>> Lib-jdk.jdwp.agent.gmk :
>>>>
>>>> 30 $(eval $(call SetupJdkLibrary, BUILD_LIBDT_SOCKET, \
>>>> ......
>>>> 33 CFLAGS := $(CFLAGS_JDKLIB) -DUSE_MMAP \
>>>>
>>>>
>>>> Any objections  to remove those  2    -DUSE_MMAP    settings ?
>>>> If it is fine to remove I would prepare a  webrev .
>>>>
>>>> Thanks, Matthias
>>>