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

[Magnus Ihse Bursie]

Looks good to me. 

/Magnus

> 3 aug. 2018 kl. 00:21 skrev David Holmes <david.holmes at oracle.com>:
> 
>> On 3/08/2018 4:59 PM, Baesken, Matthias wrote:
>> Thank  you  David ,  can the change be pushed ,  or do I need a second review for an XS change  ?
>> (any way a second review would be good 😊 )
> 
> Need a review from official build team member :)
> 
> Cheers,
> David
> 
>> Best regards, Matthias
>>> -----Original Message-----
>>> From: David Holmes <david.holmes at oracle.com>
>>> Sent: Freitag, 3. August 2018 08:18
>>> To: Baesken, Matthias <matthias.baesken at sap.com>; Magnus Ihse Bursie
>>> <magnus.ihse.bursie at oracle.com>
>>> Cc: build-dev at openjdk.java.net
>>> Subject: Re: RFR [XS]: 8208744: remove unneeded -DUSE_MMAP settings for
>>> JDK native libs builds -was : RE: unneeded -DUSE_MMAP in JDK native libs
>>> builds
>>> 
>>> 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
>>>>>>