Porting Hotspot to other platforms / OS'es

[Michael Neuweiler]

Hi Andrew,

Thanks a lot for your fast response. I do share your opinion that 
building/bootstrapping at least the hotspot must _not_ rely on any other 
java technology but solely on the standard GNU toolchain (or similar). 
If the build of hotspot with gcc/gcj is possible, I wouldn't mind 
copying jar's over from an existing installation. That'd be ok - but no 
libraries or other platform/OS dependant binary.

In the meantime I discovered the porters-dev mailinglist where I was 
able to find dome interesting information and one possible solution 
(although it requires some special tweaks with a customized linux shell, 
ssh and nfs to the target environment) : 
http://mail.openjdk.java.net/pipermail/porters-dev/2008-February/000080.html

I will also check with the developers of Haiku 
(http://mail.openjdk.java.net/pipermail/porters-dev/2008-January/000055.html) 
and the porters to MIPS 
(http://mail.openjdk.java.net/pipermail/porters-dev/2008-April/000131.html) 
to find out more.

I'll keep you informed on my progress and once I'm "blissed" with 
success I'll write a guide which could be added to the FAQ section.

Regards,
 Michael

Andrew John Hughes wrote:
> On 21/05/2008, Michael Neuweiler <michael at neuweiler.biz> wrote:
>   
>>  Hi,
>>
>>  I wanted to start porting OpenJDK to Syllable on Intel32 but got stuck with
>> the chicken and egg problem of hotspot: "you need a running JDK to build a
>> new one".
>>
>>  What are your recommendations to start a port? Is cross-compiling the only
>> solution or are there other ways?
>>  I think I saw once that an XSLT is started with an already installed
>> JRE/JDK during the build process on my Linux machine. Is this the only
>> reason why a JRE has to be installed?
>>
>>  Any help would be greatly appreciated!
>>
>>  Regards,
>>   Michael Neuweiler
>>
>>
>>     
>
> (Adding distro-pkg-dev too)
>
> My understanding, both from building OpenJDK quite a number of times
> and from my own general thoughts on the issues of building a Java
> environment, is that bootstrapping the JDK through its standard build
> process is more than just handling XSLT.
>
> The first thing you're likely to run across is that there are no
> current Java compilers (as far as I know) that are not written in Java
> -- the main two are ecj from Eclipse and javac itself.  The first
> thing the OpenJDK build process does is build javac and the other
> language tools.  The current build not only depends on an existing
> javac to do this,  but a full-scale JDK to run ant.  My personal
> feelings are that it would have been better to stick with make for the
> langtools, but oh well...
>
> If my memory serves correctly, this is followed by JAXWS and JAXP,
> both of which require Java.  Thus, a sensible course of action might
> be to approach building HotSpot alone first.  Assuming this is
> possible (I have my doubts about it also including Java code), you
> could then use this to run an existing JAR file containing the tools
> to build.
>
> The reason I've CCed distro-pkg-dev on this is that a lot of work on
> bootstrapping on unsupported architectures (mainly the CPU rather than
> the OS) has been done under the auspices of the IcedTea
> (http://icedtea.classpath.org/) project.  Here, we've found gcj to be
> useful in breaking this bootstrapping cycle -- do you know if GCC
> (which includes gcj) is available for the platform you are working on?
> This might be the simplest course of action.
>
> Looking forward to hearing how this works out for you,
>   
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