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From Xiao-Feng Li <xiaofeng...@gmail.com>
Subject Re: Question about the boot and classloading
Date Tue, 19 May 2009 01:48:44 GMT
On Mon, May 18, 2009 at 8:37 PM, tian galaxy <harmonymail.ty@gmail.com> wrote:
> Yes , implement osgi loading model in there is too complex.
>
> We know some modules are more important than others , performing some
> fundamental , basic functions .
> Is it possible to only load these more" basic " modules with bootstrap class
> loader and make the other modules work the osgi bundle?
> Actually I don't quite understand why system classes could only be loaded by
> bootstrap class loader?I noticed that there are some safety concerns
> ,is there any reasons other than that?

In my understanding, the reason is the system has to have a "ready
environment" for Java domain to stand. For example, every class is
described by j.l.Class, which should be described by itself; and every
type is a sub(..)class of j.l.Object, which is a subclass of itself.
So the system has to load those classes before it knows what is
j.l.Class and j.l.Object. The same logic applies to those primitive
data types, some data structures that describe the data structures,
etc. Finally you probably need to load other class loader with the
bootstrap loader before you can use the other class loader. :)

Thanks,
xiaofeng

> Thanks !
>
>
> 2009/5/18 Pavel Pervov <pmcfirst@gmail.com>
>
>> Short answer is "no". You'll have to implement osgi loading model
>> inside bootstrap classloader. Is it too complex?
>>
>> 2009/5/18, tian galaxy <harmonymail.ty@gmail.com>:
>> > Hi Pavel.
>> >
>> > Thanks.
>> > Yes ,that's right .My question is whether there is a way to load the
>> system
>> > class by class loader other than the  bootstrap class loader ?
>> > If we could load the system class by different loaders other than the
>> > bootstrap class loader then there is a chance to make the harmony runtime
>> to
>> > be osgi-ed.
>> > I trying to work on this problem . Do you have any suggestions ?
>> >
>> >
>> > 2009/5/18 Pavel Pervov <pmcfirst@gmail.com>
>> >
>> >> Tian,
>> >> System classes are all loaded with bootstrap classloader. It is
>> >> written in C++ and is located in
>> >> working_vm/vm/vmcore/src/class_support/classloader.cpp
>> >>
>> >> 2009/5/17, tian galaxy <harmonymail.ty@gmail.com>:
>> >> > Hi all
>> >> > I have a question about the classloading in the drlvm.
>> >> >
>> >> > I know that there are kernel library inside the drlvm such as
>> >> > java.lang.classloader, which enclose the the systemclassloader. And
>> this
>> >> > class is loaded and used in the process of creating VM .
>> >> > While the systemclassloader is a subtype of urlclassloader which is
in
>> >> the
>> >> > "luni" module.So does the JNI_CreateJavaVM
>> >> > also load the urlclassloader in the boot procedure of vm ?(I failed
to
>> >> > search related code in the source code of drlvm).
>> >> > If so , when ?Before or after the jni available ?
>> >> > Since I am trying to implement the osgi on harmony and the osgi works
>> >> with
>> >> > bundles (modules) , I think I need to know the procedure of booting
>> and
>> >> > loading of class from different modules at the start up time.
>> >> > Any clue about this ?Thanks
>> >> >
>> >> > plus,do we have the source code of java.exe ?Where?
>> >> >
>> >> > --
>> >> > Regards
>> >> > Michael Tian
>> >> >
>> >>
>> >
>> >
>> >
>> > --
>> > Regards
>> > Michael Tian
>> >
>>
>
>
>
> --
> Regards
> Michael Tian
>



-- 
http://people.apache.org/~xli

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