RFR(L): 8031581: PPC64: Addons and fixes for AIX to pass the jdk regression tests

Volker Simonis volker.simonis at gmail.com
Tue Jan 14 08:40:55 UTC 2014


could you please review the following changes for the ppc-aix-port
stage/stage-9 repositories (the changes are planned for integration into
ppc-aix-port/stage-9 and subsequent backporting to ppc-aix-port/stage):


I've build and smoke tested without any problems on Linux/x86_64 and PPC64,
Windows/x86_64, MacOSX, Solaris/SPARC64 and AIX7PPC64.

With these changes (and together with the changes from "8028537: PPC64:
Updated jdk/test scripts to understand the AIX os and environment" and
"8031134 : PPC64: implement printing on AIX") our port passes all but the
following 7 jtreg regression tests on AIX (compared to the Linux/x86_64
baseline from www.java.net/download/jdk8/testresults/testresults.html‎):

java/nio/channels/AsynchronousChannelGroup/Basic.java (sporadically)
java/nio/channels/AsynchronousChannelGroup/Unbounded.java (sporadically)
sun/security/krb5/auto/Unreachable.java (only on IPv6)

Thank you and best regards,

Following a detailed description of the various changes:

   - According to ISO C it is perfectly legal for malloc to return zero if
   called with a zero argument. Fix various places where malloc can
   potentially correctly return zero because it was called with a zero
   - Also fixed DiagnosticCommandImpl.c to include stdlib.h. This only
   fixes a compiler warning on Linux, but on AIX it prevents a VM crash later
   on because the return value of malloc() will be casted to int which is
   especially bad if that pointer was bigger than 32-bit.


   - Also use PollingWatchService on AIX.


   - Put the implementation for the native methods of NativeThread into
   AixNativeThread.c on AIX.


   - On AIX, the constants used for the polling events (i.e. POLLIN, POLLOUT,
   ...) are defined to different values than on other operating systems. The
   problem is however, that these constants are hardcoded as public final
   static members of various, shared Java classes. We therefore have to map
   them from Java to native every time before calling one of the native poll
   functions and back to Java after the call on AIX in order to get the right


   - As discussed on the core-libs mailing list (see
   it is not necessary to call Files.getFileAttributeView() with any
   linkOptions because at that place we've already checked that the target
   file can not be a symbolic link. This change makes the implementation more
   robust on platforms which support symbolic links but do not support the
   O_NOFOLLOW flag to the open system call. It also makes the JDK pass the
   demo/zipfs/basic.sh test on AIX.


   - Support "compound text" on AIX in the same way like on other Unix


   - Define the correct attach provider for AIX.


   - AIX needs a workaround for I/O cancellation (see:
   "..The close() subroutine is blocked until all subroutines which use the
   file descriptor return to usr space. For example, when a thread is calling
   close and another thread is calling select with the same file descriptor,
   the close subroutine does not return until the select call returns...". To
   fix this problem, we have to use the various NET_ wrappers which are
   declared in net_util_md.h and defined in aix_close.c and we also need
   some additional wrappers for fcntl(), read() and write() on AIX.
   While the current solution isn't really nice because it introduces some
   more AIX-specifc sections in shared code, I think it is the best way to go
   for JDK 8 because it imposes the smallest possible changes and risks for
   the existing platforms. I'm ready to change the code to unconditionally use
   the wrappers for all platforms and implement the wrappers empty on
   platforms which don't need any wrapping. I think it would also be nice to
   clean up the names (e.g. NET_Read() is currently a wrapper for recv()and the
   NET_ prefix is probably not appropriate any more so maybe change it to
   something like IO_). But again, I'll prefer to keep that as a follow up
   change for JDK9.
   - Calling fsync() on a "read-only" file descriptor on AIX will result in
   an error (i.e. "EBADF: The FileDescriptor parameter is not a valid file
   descriptor open for writing."). To prevent this error we have to query if
   the corresponding file descriptor is writeable. Notice that at that point
   we can not access the writable attribute of the corresponding file
   channel so we have to use fcntl().


   - On AIX the implementation is especially tricky, because the
close()system call will block if another thread is at the same time
blocked in a
   file operation (e.g. 'read()') on the same file descriptor. We therefore
   combine the AIX ProcessPipeInputStream implemenatation with the
   DeferredCloseInputStream approach used on Solaris (see
   UNIXProcess.java.solaris). This means that every potentially blocking
   operation on the file descriptor increments a counter before it is executed
   and decrements it once it finishes. The 'close()' operation will only be
   executed if there are no pending operations. Otherwise it is deferred after
   the last pending operation has finished.


   - On AIX we have to call shutdown() on a socket descriptor before
   closing it, otherwise the close() call may be blocked. This is the same
   problem as described before. Unfortunately the JDI framework doesn't use
   the same IO wrappers like other class library components so we can not
   easily use the NET_ abstractions from aix_close.c here.
   - Without this small change all JDI regression tests will fail on AIX
   because of the way how the tests act as a "debugger" which launches another
   VM (the "debugge") which connects itself back to the debugger. In this
   scenario the "debugge" can not shut down itself because one thread will
   always be blocked in the close() call on one of the communication


   - Set the scope identifier for IPv6 addresses on AIX.


   - It turns out that we do not always have to replace SO_REUSEADDR on AIX
   by SO_REUSEPORT. Instead we can simply use the same approach like BSD
   and only use SO_REUSEPORT additionally, if several datagram sockets try
   to bind to the same port.
   - Also fixed a comment and removed unused local variables.
   - Fixed the obviously inverted assignment newTime = prevTime; which
   should read prevTime = newTime;. Otherwise prevTime will never change
   and the timeout will be potential reached too fast.


   - AIX does not understand /proc/self so we have to query the real
   process ID to access the proc file system.


   - On AIX, connect() may legally return EAFNOSUPPORT if called on a
   socket with the address family set to AF_UNSPEC.

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