libunwind & _Unwind_Backtrace
Bryce McKinlay
mckinlay@redhat.com
Wed May 18 23:00:00 GMT 2005
Steve Ellcey wrote:
>I was looking at building java on IA64 HP-UX and I found that the java
>library calls _Unwind_Backtrace(). Now the unwind interface for C++ is
>standardized and does not include this routine, apparently this was
>added for java but isn't part of any standard.
>
>The reason this affects me is that on IA64 HP-UX we are currently using
>the system libunwind and it does not include this routine. So, to build
>java on IA64 HP-UX I have to provide this somehow. I am looking at
>several options and would like some opinions.
>
>Create my own _Unwind_Backtrace routine separate from libunwind. This
>should be possible using the existing system interface to libunwind,
>but where would it live then? Could I put it in the java runtime
>library?
>
There is something of a mechanism to define your own, platform specific
backtrace routine. Currently, this is just a minimal implementation used
on Windows where real unwind info is unavailable. However, it could be
extended/improved to provide a complete replacement for the gcc unwind
functions if needed.
Note that you'll need to implement _Unwind_GetIP() and
_Unwind_GetRegionStart() in addition to _Unwind_GetBackTrace in order to
get full functionality.
See fallback_backtrace in stacktrace.cc, sysdep/i386/backtrace.h, and
configure.host for some pointers.
Regards
Bryce
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