Building programs with MODE=shared in L4Re

Adam Lackorzynski adam at os.inf.tu-dresden.de
Fri Jun 8 00:32:04 CEST 2018


On Sun May 20, 2018 at 00:47:02 +0200, Paul Boddie wrote:
> On Monday 14. May 2018 21.18.04 Adam Lackorzynski wrote:
> > 
> > You can set LD_DEBUG=1 in the environment of your program to make the
> > dynamic loader tell you something. LD_TRACE_LOADED_OBJECTS=1 might also
> > be of help. Add enviroment variable settings after the program's
> > cmdline: ...:start({ ...}, "rom/myprog arg", { LD_DEBUG=1, ... });
> 
> So, with the help of fbterminal (mentioned in my last message), I managed to 
> get some debugging information out of the loader:
> 
> L4Re: rom/ex_hello_shared: Unhandled exception: PC=0x800000 PFA=8d7a LdrFlgs=0
> 
> This appears to be generated in pkg/l4re-core/l4re_kernel/server/src/region.cc 
> inside the Region_map::op_exception method. I'm not really sure what I can do 
> with this information, though.
> 
> Alongside ex_hello_shared and the stack of programs supporting the framebuffer 
> environment, I have the following libraries included in the modules.list:
> 
> module lib4re.so
> module lib4re-util.so
> module libc_be_l4refile.so
> module libc_be_l4re.so
> module libc_be_socket_noop.so
> module libc_support_misc.so
> module libdl.so
> module libl4sys-direct.so
> module libl4sys.so
> module libl4util.so
> module libld-l4.so
> module libpthread.so
> module libsupc++.so
> module libuc_c.so
> 
> This being for reference, since my first guess would be that the loader is 
> failing before even considering any of the libraries.

So the "Unhandled exception" message is the first one, or are there
other messages? For me this works, in QEMU. If there would be a lib
missing or similar it would also complain differently.


Adam



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