Aborted L4linux due to CLI/STI

Adam Lackorzynski adam at os.inf.tu-dresden.de
Mon Sep 8 00:29:18 CEST 2014


On Fri Sep 05, 2014 at 16:21:34 +0000, Masti  Ramya Jayaram wrote:
> I forgot to mention that it also does not support the traditional
> cmpxchg instructions using the lock line. That is why I disabled it.

That's ok as long it's also ok for native Linux.

> > On 05 Sep 2014, at 18:16, "Masti  Ramya Jayaram" <rmasti at inf.ethz.ch> wrote:
> > 
> > Dear all,
> > 
> > I get an error during L4linux boot when I enter the debugger (using ESC) and resume:
> > 
> > Aborted L4linux due to CLI/STI at 0x534911. 
> > 
> > When I disassemble this using gdb:
> > 
> > (gdb) disassemble 0x534911
> > Dump of assembler code for function cmpxchg8b_emu:
> >   0x00534910 <+0>:    pushf  
> >   0x00534911 <+1>:    cli    
> >   0x00534912 <+2>:    cmp    (%esi),%eax
> >   0x00534914 <+4>:    jne    0x534922 <cmpxchg8b_emu+18>
> >   0x00534916 <+6>:    cmp    0x4(%esi),%edx
> >   0x00534919 <+9>:    jne    0x534924 <half_same>
> >   0x0053491b <+11>:    mov    %ebx,(%esi)
> >   0x0053491d <+13>:    mov    %ecx,0x4(%esi)
> >   0x00534920 <+16>:    popf   
> >   0x00534921 <+17>:    ret    
> >   0x00534922 <+18>:    mov    (%esi),%eax
> >   0x00534924 <+0>:    mov    0x4(%esi),%edx
> >   0x00534927 <+3>:    popf   
> >   0x00534928 <+4>:    ret    
> > 
> > When I built l4linux, I had to disable CONFIG_X86_CMPXCHG,
> > CONFIG_CMPXCHG_LOCAL and  CONFIG_X86_CMPXCHG64 despite building for
> > the Pentium because my processor does not support PAE (which is the
> > option that enables this). I am guessing This is the reason it tries
> > to emulate the CMPXCHG instructions.
> > 
> > What is the correct l4linux configuration to use for a machine that
> > does not support any of the atomic instructions like CMPXCHG8,
> > ATOMIC, etc.?

Which processor type did you select?
In L4Linux, there's an adapted version of the cmpxchg8b_emu code that is
enabled if CONFIG_X86_CMPXCHG64 is not set. I'm wondering how did you
end up with the code containing the cli? In L4Linux this part is
replaced.




Adam
-- 
Adam                 adam at os.inf.tu-dresden.de
  Lackorzynski         http://os.inf.tu-dresden.de/~adam/



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