[ELDK] Fwd: OpenJDK and Other Questions

[Jason Hanna]

Thanks Wolfgang.

I've been wondering about how large the performance penalty might
be...and was already planning to pick up a 440-series board with a FPU
soon in order to do some benchmarking.

My initial hope was that we could avoid most floating-point operations
in our developed code. Not sure however if there other places in the
open source platforms I'm aiming to use - or the underlying VM where
it would be impossible to avoid FP maths.

SSL/TLS and encryption operations will also likely be a problem. I
don't know much about the Turbo Security Engine that ships with 440EPx
but it seems like that might be a necessity provided it works properly
with the operating system and VM.

If anyone is interested please let me know and I'll be happy to share
some of my findings, progress updates, etc.

-jmh



On Thu, Sep 18, 2008 at 11:08 AM, Wolfgang Denk <wd at denx.de> wrote:
> Dear Jason,
>
> In message <8f9e78f00809180534o43acd6d2v4087a3360e068943 at mail.gmail.com> you wrote:
>>
>> Before attempting to make GCJ work I'm going to try running Debian
>> Lenny on my Kilauea board. I built a Lenny VM yesterday on my
>> workstation and got OpenJDK/IcedTea running quite easily. Next step is
>> try and run a similar configuration on my embedded system.
>
> Keep in mind that the Kilauea is a 405 which means it has small cache
> lines (which may or may not be dealt with correctly by  your  version
> of  glibc),  and  it  has  no  FPU,  which  means you must enable FPU
> emulation in the kernel which is a real  pain  in  ...  in  terms  of
> performance  -  the overhead of trapping into kernelmode for each and
> every floating point instruction is HUGE.
>
>
> Note that ELDK for 4xx is configured to use software floating-point,
> which is much more efficient.
>
> Best regards,
>
> Wolfgang Denk
>
> --
> DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
> HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
> Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
> PoB = "Prisoner of Bill" -- those held captive, unwillingly or other-
> wise, by the contemptible Microsoft monopoly.
>         -- Tom Christiansen in <6abo45$3lc$2 at csnews.cs.colorado.edu>
>