sablevm-developer

[Sablevm-developer] Porting sablevm to powerpc

[Mark W. <ma...@kl...>]

Hi (reply to sablevm-developer original message was on debian lists),

On Thu, 2002-08-15 at 02:14, Grzegorz Prokopski wrote:
> 
> So I took some time to check what that "easily portable" means in
> practise - and started porting this JVM to alpha.
> 
> It was my first time I was doing a port and I never wrote in alpha's
> assembler, so it took very long - about 24 hours and resulted (of
> mostly learning) in small diff (around 100 lines, but there was some
> code reorganizing in it too, so real diff was around 25 lines!)
> 
> <blink><B>25 lines to port JVM to new architecture</B></blink>
> 
> Anyway - now SableVM JVM supports ia32 and alpha.
> Official 1.0.2 release will be made soon.
> 
> More arches will come.

Impressive! I am very interested in a VM that uses GNU Classpath and
that I can use on powerpc (Debian GNU/Linux system).
What 25 lines of code do I have to look at?

I have no experience with powerpc assembly so if anybody has references
that would be greatly appreciated.

I would use it to finally setup a autobuilder/tester for Classpath CVS
as I have currently running (on that powerpc machine) for libgcj (which
has still a long way to go for being completely merged with GNU
Classpath).

Cheers,

Mark

Re: [Sablevm-developer] Porting sablevm to powerpc

[Etienne M. G. <eti...@uq...>]

Hi Mark.

Grzegorz told me he would be away from his email for a few days, (I
should be too, very soon), so I will reply to your message, as I think
this reply might benefit other potential porters..

On Thu, Aug 15, 2002 at 10:43:05PM +0200, Mark Wielaard wrote:
> Impressive! I am very interested in a VM that uses GNU Classpath and
> that I can use on powerpc (Debian GNU/Linux system).
> What 25 lines of code do I have to look at?

You have to look at the following files:

src/libsablevm/include/jni_system_specific.h
src/libsablevm/system.h
src/libsablevm/system.c

The easiest would be to forget about inline-threaded engine for now.
It should take me at most a few minutes to fix it on the powerpc, once
the remaining is in place; I have to add calls to _svmf_iflush in
_svmf_get_sequence. _svmf_iflush already has a draft implementation
for powerpc.  I have already setup the configure.ac stuff to select
the direct-threaded engine by default for non i*86-*-gnu systems.

The single most difficult part of porting SableVM to a new system, is
implementing the _svmh_compare_and_swap function, which ***MUST*** be
an *ATOMIC* operation.

[Note: You also have to worry about the _svmf_iflush stuff when you
want to run the inline-threaded engine on processors with distinct
instruction and data caches.]

I hope this helps.

Etienne
-- 
Etienne M. Gagnon                    http://www.info.uqam.ca/~egagnon/
SableVM:                                       http://www.sablevm.org/
SableCC:                                       http://www.sablecc.org/

Re: [Sablevm-developer] Porting sablevm to powerpc

[Mark W. <ma...@kl...>]

Hi,

On Thu, 2002-08-15 at 23:46, Etienne M. Gagnon wrote:
> On Thu, Aug 15, 2002 at 10:43:05PM +0200, Mark Wielaard wrote:
> > Impressive! I am very interested in a VM that uses GNU Classpath and
> > that I can use on powerpc (Debian GNU/Linux system).
> > What 25 lines of code do I have to look at?
> 
> You have to look at the following files:
> 
> src/libsablevm/include/jni_system_specific.h
> src/libsablevm/system.h
> src/libsablevm/system.c

OK, after spending a couple of hours learning powerpc assembly and the
gcc asm constraints I think that I have something that might be what is
needed for powerpc. Unfortunately it doesn't work correctly yet, but
looking at the output of --verbose I get the impression that we are
almost there. Here are the last 15 lines for sablevm --verbose Hello:

[verbose class: creating "[Ljava/util/Hashtable$HashEntry;"]
[verbose class: loading "java/util/StringTokenizer"]
[verbose class: loading "java/util/Enumeration"]
[verbose class: creating "[Ljava/lang/String;"]
[verbose class: loading "java/lang/StringBuffer"]
[verbose class: loading "java/lang/VMSecurityManager"]
[verbose class: loading "java/util/WeakHashMap$WeakBucket$WeakEntry"]
[verbose class: loading "java/io/BufferedInputStream"]
[verbose class: loading "java/io/FilterInputStream"]
[verbose class: loading "java/io/InputStream"]
[verbose class: loading "java/io/FileInputStream"]
[verbose class: loading "java/io/FileDescriptor"]
[verbose class: loading "java/lang/SecurityException"]
java/lang/ExceptionInInitializerError
[verbose gc: total gc time = 0 sec 0 usec]

Attached are my versions of the above files. If there is someone with
some powerpc knowledge on the list then I would highly appreciate it if
you could take a look.

Have to get some sleep now.

Cheers,

Mark 

Re: [Sablevm-developer] Porting sablevm to powerpc

[Grzegorz P. <ga...@de...>]

W li=B6cie z nie, 18-08-2002, godz. 02:02, Mark Wielaard pisze:=20
> OK, after spending a couple of hours learning powerpc assembly and the
> gcc asm constraints I think that I have something that might be what is
> needed for powerpc. Unfortunately it doesn't work correctly yet, but
> looking at the output of --verbose I get the impression that we are
> almost there. Here are the last 15 lines for sablevm --verbose Hello:
It looks like PowerPC is the first big-endian system SableVM is being
compiled on. We can suspect that it is causing some problems.
Don't know exactly how's that about PowerPC accepting both big and
low-endian data[1] in Linux.

I checked data sizes for types used in jni_system_specific.h - they
_are_ the same as for ia32 and alpha, so no mistake there.
page size _is_ 4 kb according to [2].

about your assembler code - if you're not sure if it works:
1) ask at some devel/port list, for ex. debian-powerpc@l.d.o.

2) you could also _for testing only_ disable assembler stuff
and put "C" version there. If it sometimes goes beyond the
point it is now - then it's sth. wrong with this assembler part.

Keep in mind that if you do that - SableVM will probably randomly
break in different places or sth.

I have requested installation of build-depends of SableVM on
PowerPC(unstable), ia64(woody) and hppa(woody) debian developer's
machines.

PowerPC - because you started it and I'd like to test it too.
ia64 - because it's crucial to get _this_ arch working - we all
  will be using it (at some point in the future)
hppa - because it's already using gcc 3.x - and there can be some
  interesting differences to work out (may be), however I don't expect
  too much of them. Anyway - transition to gcc 3.2 for all debian arches
  will start soon.

I'll send a status report as soon as I have sth interesting ;-)

That's really great you started the PowerPC port.
Keep up with it!

Regards

					Grzegorz B. Prokopski


[1]
http://developer.apple.com/techpubs/hardware/DeviceManagers/pci_srvcs/pci_c=
ards_drivers/PCI_BOOK.24e.html
[2] http://www.cwi.nl/~manegold/Calibrator/DB/DB.shtml