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.hol...@oracle.com> > Sent: Freitag, 3. August 2018 02:56 > To: Magnus Ihse Bursie <magnus.ihse.bur...@oracle.com>; Baesken, > Matthias <matthias.baes...@sap.com> > Cc: build-dev@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.baes...@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 > >