Hello scenario gets stuck

[Markus Partheymueller]

When I enable pagefault tracing, the last one I see is a fault at address
0xffffffff on that instruction. The respective source code is in
/pkg/cxx/lib/tl/include/list_alloc:L182. I assume dereferencing c in
c->next is the problem?


On 4 June 2013 00:40, Adam Lackorzynski <adam at os.inf.tu-dresden.de> wrote:

> On Mon Jun 03, 2013 at 16:22:54 +0200, Markus Partheymueller wrote:
> > I'm having trouble booting the hello example on real hardware. The
> > following config is booted via PXE:
> >
> > addr   0x2000000
> > exec   mparthey/foc/bootstrap -serial
> > load    mparthey/foc/fiasco -serial -serial_esc -esc
> > load    mparthey/foc/sigma0
> > load    mparthey/foc/moe
> > load    mparthey/foc/l4re
> > load    mparthey/foc/hello
> >
> > But it hangs after "MOE: Hello world". I can still enter the Kernel
> > debugger, listing these task and thread objects:
> >
> > [Objects]
> >        1 f007e020 [Task   ] {KERNEL} R=2
> >        6 ffdc6134 [Thread ] {KERNEL} C=0 R=1 current
> >        7 fffe8f70 [Task   ] {sigma0          } R=3
> >        8 ffd80134 [Thread ] {sigma0          } C=0 S=D:7 R=3
> >        9 fffe8f18 [Task   ] R=3
> >        a ffd83134 [Thread ] C=0 S=D:9 R=4
> >
> > Backtrace on thread a yields an address 0x143d7d in moe (?), belonging to
> >
> > void
> > List_alloc::merge()
> > {
> >   List_alloc_sanity_guard __attribute__((unused)) guard(this, __func__);
> >   Mem_block *c = _first;
> >   while (c && c->next)
> >   143d7d:       8b 00                   mov    (%eax),%eax
> >   143d7f:       85 c0                   test   %eax,%eax
> >   143d81:       75 ee                   jne    143d71
> > <_ZN22Single_page_alloc_base5_freeEPvmb+0x51>
> > _ZN22Single_page_alloc_base5_freeEPvmb():
> > [...]/src/l4/pkg/moe/server/src/page_alloc.cc:109
> > }
> >
> > On a different machine the exact same setup works fine. Has anyone got a
> > clue what goes wrong here? If I should get more information out of the
> > kernel debugger, just let me know.
>
> My first guess would be that it's pagefaulting on that instruction.
> Could you check whether this is the case and what the of value eax/pfa
> is?
>
>
>
> Adam
> --
> Adam                 adam at os.inf.tu-dresden.de
>   Lackorzynski         http://os.inf.tu-dresden.de/~adam/
>
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