[vmkit-commits] About j3-64bit crush

[Will Dietz]

Recompiling classpath with framepointers as you suggested fixed my
64bit j3 nicely!

Just wanted to thank you for sharing this :)

~Will

On Sun, Jul 18, 2010 at 8:19 PM, Allan Tong <actong88 at gmail.com> wrote:
> On Fri, Jul 16, 2010 at 10:44 AM, Minas Abrahamyan <minas.subs at gmail.com> wrote:
>> Crush occurs within j3::Jnjvm::loadBootstrap():
>> when running Class::initialiseClass() of last macro
>> LOAD_CLASS(upcalls->SystemClass)
>> but before initializing vm->appClassLoader; which would be done just
>> by the next call to loadAppClassLoader()
>> in Jnjvm.cpp.
>>
>> <<<
>> native compile java/lang/VMRuntime.nativeLoad()
>> --> end of native compile java/lang/VMRuntime.nativeLoad()
>> [Switching to Thread 0x1200ff700 (LWP 11395)]
>>
>> Breakpoint 1, Java_java_lang_VMRuntime_nativeLoad (str=0x7ffff020b750,
>> javaLoader=0x0)
>>    at ClasspathVMRuntime.inc:113
>>>>>
>> ...many debugging results skipped...
>>
>> Fruitful was comparison with 32-bit version - as it's working.
>>
>> And I've found that Problem is FindClass does not load class
>> "gnu/classpath/Pointer64" and returns 0,
>> while the 32-bit counterpart does find and load corresponding
>> "gnu/classpath/Pointer32";
>>
>> This is result of
>> UserClass* currentClass = th->getCallingClassLevel(0);
>> in FindClass returns 0;
>> <= JavaThread::getCallingClassLevel - returns 0, since all
>> 'MethodInfo's in stack have value of MethodType==-1
>>
>> While 32-bit version finds right value from stack, right value here is
>> 'MethodInfo's with MethodType==1
>> //why not enums?
>>
>> So much for now. Something wrongly initializes type values of methods
>
> Hi,
>
> I was having the same problem here.  It turns out that the 64-bit
> build of Classpath was omitting frame pointers.  Once I recompiled
> Classpath with -fno-omit-frame-pointer, the StackWalker was able to
> get past the offending stack frame and find the calling Java method.
> This resolves the segfault, though now I get a ClassNotFoundException
> trying to find my main class, which I haven't looked into yet.
>
>  - Allan
>
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