Etienne Gagnon wrote:
>>> On the other hand, I don't
>>> understand why the hyluni library assumes that it will be necessarily
>>> loaded by a specific VM library sitting in a particular directory.
>> It doesn't. The hyluni library code uses macros that expand out to a
>> function table maintained by the VMStruct as you elude to below.
>> ...
>> The only functions that are exported by the VM are [3]
>> VMInterface* JNICALL VMI_GetVMIFromJNIEnv(JNIEnv* env)
>> VMInterface* JNICALL VMI_GetVMIFromJavaVM(JavaVM* vm)
>
> Exactly. Now, these 2 functions are global. How does the hyluni
> library resolves these two global references? As far as I can see, in
> the build/install process, the hyluni library simply assumes that the
> system's dynamic linker will resolve them assuming they reside in a
> specific file. See build.xml:
>
> <!-- Don't copy the VMI library. the one we build is a stub that is
> replaced by a concrete implementation by the VM-implementor -->
> <patternset excludes="*vmi*${shlib.suffix}*" />
>
> Unless I am missing something?
Ah, ok. So as you have probably seen, the versions in the Harmony SVN
are stubs that return NULL; hence the comment above not to copy the
stubs into the runtime layout.
The actual implementation are provided by the VM in a DLL loaded by the
Harmony launcher[1]. At launch time the DLL is loaded (and the VMI
functions globally exported).
There is a default directory and DLL name built into the launcher:
...
char defaultDllName[] = "clearvm";
char defaultDirName[] = "default";
...
and the user can override these with command-line arguments to launch a
different VM / specify a different VM DLL, like this:
java -vmdir:<sablevm> -vm:<hyvmdll>
>>> The problem I see, with the current approach, is that it makes it
>>> impossible to provide distinct VM libraries for different purposes
>>> (debugging, faster execution, profiling, ...), as they can't be all in a
>>> single file.
>>
>> We want that too, and I believe that it is already possible.
>
> I am surely missing something...
Does that resolve it?
Regards,
Tim
Refs:
[1]
http://svn.apache.org/viewcvs.cgi/incubator/harmony/enhanced/classlib/trunk/native-src/shared/launcher/main.c?view=markup
--
Tim Ellison ([EMAIL PROTECTED])
IBM Java technology centre, UK.
