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Message-ID: <004f01c459f5$05efd5c0$5f8401c1@elmoii>
From: "Alan Larkin" <nobrow AT eircom DOT net>
To: <cygwin AT cygwin DOT com>
References: <005301c459e6$1eeec090$5f8401c1 AT elmoii> <Pine DOT GSO DOT 4 DOT 58 DOT 0406240935120 DOT 28578 AT slinky DOT cs DOT nyu DOT edu>
Subject: Re: Old Cygwin Versions -or- Elusive Compatability Problem
Date: Thu, 24 Jun 2004 15:10:37 +0100
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> FWIW, I didn't find a -Xrun flag in the Sun JDK.  I did find a -Xrunhprof
> flag, which doesn't seem to allow running an external program...  You
> should let the list know if you're using another JDK.  BTW, from your
> description above, it's unclear whether you actually run an executable, or
> dynamically load a DLL.  If the latter, you should know that the Cygwin
> DLL is not amenable to dynamic loading, and there are no plans to fix it
> ATM.

I never noticed that its not in the help before, but I assure you that Sun
JVMs support it (-Xrunhprof is a particular instance that loads hprof.dll, a
profiler built in exactly the same manner as mine). Its a DLL. If I invoke

java -Xruncygforrest-0:<options> HelloWorld

(or more simply

java -Xruncygforrest-0:help

to print out my profilers help message)

the JVM looks for a hook in forrest.dll which sets things in motion. I have
seen all sorts of crashes and error messages whilst developing this, but its
just so queer to see nothing!

The Cygwin DLL must be dynamically loading ...

$ nm ./cygforrest-0.dll | grep -C 2 cygwin
10047d40 B __bss_end__
10043000 B __bss_start__
10018630 T __cygwin_crt0_common AT 8
10018030 T __cygwin_dll_entry AT 12
10018100 T __cygwin_noncygwin_dll_entry AT 12
10040184 D __data_end__
10040000 D __data_start__
--
10018600 T __fopen64
10018610 T __fstat64
10049000 I __head_cygwin1_dll
10049014 I __head_libkernel32_a
10000000 A __image_base__
--
100491dc I __imp__calloc
100491e0 I __imp__closedir
100491e4 I __imp__cygwin_detach_dll
100491e8 I __imp__cygwin_internal
100491ec I __imp__dlclose
100491f0 I __imp__dlerror
--
10008cb0 t _canonicalize_path
10018210 T _closedir
10049890 I _cygwin1_dll_iname
100185c0 T _cygwin_attach_dll
100185b0 T _cygwin_detach_dll
10018830 T _cygwin_internal
10018820 T _cygwin_premain0
10018810 T _cygwin_premain1
10018800 T _cygwin_premain2
100187f0 T _cygwin_premain3
10043150 b _default_preloaded_symbols
10018330 T _dlclose

Maybe this was possible up to but not after version 1.5.5? Might that be the
cause?

I appreciate your help,

Alan.


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