Re: [Ikvm-developers] RXTX already loaded in another classloader

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Jim,

It's not a GNU Classpath issue, the stack walking mechanism is up to the VM to implement.

IKVM relies on the System.Diagnostics.StackFrame .NET API to walk the stack and there may be a difference (which isn't necessarily a bug) in how that behaves on Mono's ARM implementation.

Anyway, it's good that the workaround works.

Regards,
Jeroen

> -----Original Message-----
> From: Jim Redman [mailto:jr...@er...]
> Sent: Sunday, May 25, 2008 16:31
> To: Jeroen Frijters
> Cc: ikv...@li...
> Subject: Re: [Ikvm-developers] RXTX already loaded in another
> classloader
>
> Jeroen,
>
> Very nice workaround:
>
> // problems on ARM/GNU Classpath with StackWalking -
> System.loadLibrary( "rxtxSerial" );
> // call   Runtime.getRuntime().loadLibrary(libname,
> RXTXCommDriver.class.getClassLoader()); instead
>
> try {
>    java.lang.reflect.Method m =
> Runtime.class.getDeclaredMethod("loadLibrary", new Class[]
> {String.class, ClassLoader.class});
>    m.setAccessible(true);
>    m.invoke(Runtime.getRuntime(), new Object[] {"rxtxSerial",
> RXTXCommDriver.class.getClassLoader()});
> } catch ( Exception any ) {
>    any.printStackTrace();
> }
>
> So is this actually a GNU Classpath problem?  If so, I'll report it as
> an error over there.
>
> Thanks again,
>
> Jim
>
> Jeroen Frijters wrote:
> > Jim,
> >
> > I've thought of another possible workaround. Try replacing the
> explicit loadLibrary invocations with this:
> >
> > java.lang.reflect.Method m =
> > Runtime.class.getDeclaredMethod("loadLibrary0", Class.class,
> > String.class); m.setAccessible(true); m.invoke(Runtime.getRuntime(),
> > gnu.io.RXTXVersion.class, "rxtxSerial");
> >
> > This bypasses the stack walk and should cause the right class loader
> to be used.
> >
> > Regards,
> > Jeroen
> >
> >> -----Original Message-----
> >> From: Jim Redman [mailto:jr...@er...]
> >> Sent: Saturday, May 24, 2008 01:58
> >> To: Jeroen Frijters
> >> Cc: ikv...@li...
> >> Subject: Re: [Ikvm-developers] RXTX already loaded in another
> >> classloader
> >>
> >> Jeroen,
> >>
> >> Ubuntu 8.04 seems to work fine, and idea?  Need an NSLU2?
> >>
> >> Jim
> >>
> >> $ mono -V
> >> Mono JIT compiler version 1.9.1 (tarball) Copyright (C) 2002-2007
> >> Novell, Inc and Contributors. www.mono-project.com
> >>          TLS:           __thread
> >>          GC:            Included Boehm (with typed GC)
> >>          SIGSEGV:       altstack
> >>          Notifications: epoll
> >>          Architecture:  x86
> >>          Disabled:      none
> >>
> >> Serial Port Name "/dev/ttyS0"
> >> [17:48:28.42017 main] loadLibrary: ./librxtxSerial.so, class loader:
> >> ikvm.runtime.AssemblyClassLoader@1C86FBC0
> >> [17:48:28.45922 main] Library loaded: ./librxtxSerial.so, handle =
> >> 0x82BB8B8
> >> [17:48:28.46045 main] Calling JNI_OnLoad on: ./librxtxSerial.so
> >> Experimental:  JNI_OnLoad called.
> >> [17:48:28.55074 main] JNI_OnLoad returned: 0x00010002
> >> [17:48:28.55595 main] loadLibrary: ./librxtxSerial.so, class loader:
> >> ikvm.runtime.AssemblyClassLoader@1C86FBC0
> >> [17:48:28.55716 main] Library was already loaded: ./librxtxSerial.so
> >> [17:48:28.56624 main] Linking native method:
> >> gnu/io/RXTXVersion.nativeGetVersion()Ljava/lang/String;, class
> loader
> >> = ikvm.runtime.AssemblyClassLoader@1C86FBC0, short =
> >> Java_gnu_io_RXTXVersion_nativeGetVersion, long =
> >> Java_gnu_io_RXTXVersion_nativeGetVersion__, args = 8
> >> [17:48:28.56725 main] Native method
> >> gnu/io/RXTXVersion.nativeGetVersion()Ljava/lang/String; found in
> >> library
> >> 0x82BB8B8 (short)
> >> Stable Library
> >> =========================================
> >> Native lib Version = RXTX-2.1-7
> >> Java lib Version   = RXTX-2.1-7
> >> [17:48:28.58707 main] Linking native method:
> >> gnu/io/RXTXCommDriver.getDeviceDirectory()Ljava/lang/String;, class
> >> loader = ikvm.runtime.AssemblyClassLoader@1C86FBC0, short =
> >> Java_gnu_io_RXTXCommDriver_getDeviceDirectory, long =
> >> Java_gnu_io_RXTXCommDriver_getDeviceDirectory__, args = 8
> >> [17:48:28.58783 main] Native method
> >> gnu/io/RXTXCommDriver.getDeviceDirectory()Ljava/lang/String; found
> in
> >> library 0x82BB8B8 (short)
> >> [17:48:28.60276 main] Linking native method:
> >> gnu/io/RXTXCommDriver.testRead(Ljava/lang/String;I)Z, class loader =
> >> ikvm.runtime.AssemblyClassLoader@1C86FBC0, short =
> >> Java_gnu_io_RXTXCommDriver_testRead, long =
> >> Java_gnu_io_RXTXCommDriver_testRead__Ljava_lang_String_2I, args = 16
> >> [17:48:28.60363 main] Native method
> >> gnu/io/RXTXCommDriver.testRead(Ljava/lang/String;I)Z found in
> library
> >> 0x82BB8B8 (short)
> >> [17:48:28.61671 main] Linking native method:
> >> gnu/io/RXTXCommDriver.registerKnownPorts(I)Z, class loader =
> >> ikvm.runtime.AssemblyClassLoader@1C86FBC0, short =
> >> Java_gnu_io_RXTXCommDriver_registerKnownPorts, long =
> >> Java_gnu_io_RXTXCommDriver_registerKnownPorts__I, args = 12
> >> [17:48:28.61753 main] Native method
> >> gnu/io/RXTXCommDriver.registerKnownPorts(I)Z found in library
> >> 0x82BB8B8
> >> (short)
> >> [17:48:28.67625 main] loadLibrary: ./librxtxSerial.so, class loader:
> >> ikvm.runtime.AssemblyClassLoader@1C86FBC0
> >> [17:48:28.67697 main] Library was already loaded: ./librxtxSerial.so
> >> [17:48:28.70450 main] loadLibrary: ./librxtxSerial.so, class loader:
> >> ikvm.runtime.AssemblyClassLoader@1C86FBC0
> >> [17:48:28.70527 main] Library was already loaded: ./librxtxSerial.so
> >> [17:48:28.70724 main] Linking native method:
> >> gnu/io/RXTXPort.Initialize()V, class loader =
> >> ikvm.runtime.AssemblyClassLoader@1C86FBC0, short =
> >> Java_gnu_io_RXTXPort_Initialize, long =
> >> Java_gnu_io_RXTXPort_Initialize__, args = 8 [17:48:28.70800 main]
> >> Native method gnu/io/RXTXPort.Initialize()V found in library
> >> 0x82BB8B8
> >> (short)
> >> [17:48:28.71311 main] Linking native method:
> >> gnu/io/RXTXPort.open(Ljava/lang/String;)I, class loader =
> >> ikvm.runtime.AssemblyClassLoader@1C86FBC0, short =
> >> Java_gnu_io_RXTXPort_open, long =
> >> Java_gnu_io_RXTXPort_open__Ljava_lang_String_2, args = 12
> >> [17:48:28.71390 main] Native method
> >> gnu/io/RXTXPort.open(Ljava/lang/String;)I found in library 0x82BB8B8
> >> (short)
> >> [17:48:28.75709 Thread-3] Linking native method:
> >> gnu/io/RXTXPort.eventLoop()V, class loader =
> >> ikvm.runtime.AssemblyClassLoader@1C86FBC0, short =
> >> Java_gnu_io_RXTXPort_eventLoop, long =
> >> Java_gnu_io_RXTXPort_eventLoop__, args = 8
> >> [17:48:28.75821 Thread-3] Native method gnu/io/RXTXPort.eventLoop()V
> >> found in library 0x82BB8B8 (short)
> >> [17:48:28.78065 main] Linking native method:
> >> gnu/io/RXTXPort.nativeSetSerialPortParams(IIII)Z, class loader =
> >> ikvm.runtime.AssemblyClassLoader@1C86FBC0, short =
> >> Java_gnu_io_RXTXPort_nativeSetSerialPortParams, long =
> >> Java_gnu_io_RXTXPort_nativeSetSerialPortParams__IIII, args = 24
> >> [17:48:28.78149 main] Native method
> >> gnu/io/RXTXPort.nativeSetSerialPortParams(IIII)Z found in library
> >> 0x82BB8B8 (short)
> >>
> >> Jeroen Frijters wrote:
> >>> Jim Redman wrote:
> >>>> This seems to highlight another difference.  On Debian/ARM I have
> >>>> 1.9.1, on FC8 1.2.6, which doesn't seem to support the app.config
> -
> >>>> or I'm doing it wrong.
> >>>>
> >>>> Here's the Debian output:
> >>>>
> >>>> Serial Port Name "/dev/ttyUSB0"
> >>>> [07:29:07.27525 main] loadLibrary:
> /home/MIX_CMIX/librxtxSerial.so,
> >>>> class loader: null
> >>> [...]
> >>>> [07:29:08.14348 main] loadLibrary:
> /home/MIX_CMIX/librxtxSerial.so,
> >>>> class loader: ikvm.runtime.AssemblyClassLoader@BE18F840
> >>> The first attempt was made by the null class loader, which is very
> >> unlikely, because the bootstrap classes don't know about this
> library.
> >> So it looks very likely that it is a stack walking issue.
> >>> You could try working around it by moving the first loadLibrary
> call
> >> around.
> >>> I don't really know how to help you debug the issue and since I
> >>> don't
> >> have a Debian/ARM system I can't debug it myself either.
> >>> It would help if you could try it with Mono 1.9.1 on an x86 Linux
> >>> and
> >> see if that also has the problem, because then it would be easier to
> >> track down.
> >>> Regards,
> >>> Jeroen
> >> --
> >> Jim Redman
> >> (505) 662 5156 x85
> >> http://www.ergotech.com
>
> --
> Jim Redman
> (505) 662 5156 x85
> http://www.ergotech.com