[Caml-list] ocamlopt, and generated ASM

[Caml-list] ocamlopt, and generated ASM

[Jonathan Roewen]

Hi,

I'm having some esoteric problems with my operating system project,
and it randomly halting (i.e.: the hlt instruction issued with
interrupts off). I've tried grepping the ocaml sources, but to no
avail.

Could someone who has some in-depth knowledge of the code gneretor for
ocamlopt explain where these hlt instructions come from, and more
importantly, where abouts they are generated?

Perhaps ocaml 3.08.2 has some interesting bugs I'm not aware of?

Jonathan

Re: [Caml-list] ocamlopt, and generated ASM

[Stephane Glondu]

Jonathan Roewen wrote:
> I'm having some esoteric problems with my operating system project,
> and it randomly halting (i.e.: the hlt instruction issued with
> interrupts off). I've tried grepping the ocaml sources, but to no
> avail.
> 
> Could someone who has some in-depth knowledge of the code gneretor for
> ocamlopt explain where these hlt instructions come from, and more
> importantly, where abouts they are generated?

Where are these hlt exactly? In the asm file generated from the .ml
file? In the startup code? In the runtime library? The string "hlt"
doesn't seem to appear in ocaml (at least in version 3.08.3) source
code, so it seems very weird (even though possible) that this
instruction is generated by the compiler... Moreover, you usually need
to be in privilege level 0 (in kernel mode) to execute that
instruction, and there are not many ocamlopt-generated programmes run
in kernel mode... Maybe it is at a place which is not expected to be
reached in "normal" programme execution (such as after a call to
exit()). Are you sure this hlt comes from the ocamlopt generated code?

> Perhaps ocaml 3.08.2 has some interesting bugs I'm not aware of?

Actually, I'm working with version 3.08.3. But still, I would be
interested if you found out the problem.


-- 

Stephane Glondu.

Re: [Caml-list] ocamlopt, and generated ASM

[Stephane Glondu]

BTW, I am assuming you are working on i386 architecture.


Stephane Glondu wrote:
> Jonathan Roewen wrote:
> 
>>I'm having some esoteric problems with my operating system project,
>>and it randomly halting (i.e.: the hlt instruction issued with
>>interrupts off). I've tried grepping the ocaml sources, but to no
>>avail.
>>
>>Could someone who has some in-depth knowledge of the code gneretor for
>>ocamlopt explain where these hlt instructions come from, and more
>>importantly, where abouts they are generated?
> 
> 
> Where are these hlt exactly? In the asm file generated from the .ml
> file? In the startup code? In the runtime library? The string "hlt"
> doesn't seem to appear in ocaml (at least in version 3.08.3) source
> code, so it seems very weird (even though possible) that this
> instruction is generated by the compiler... Moreover, you usually need
> to be in privilege level 0 (in kernel mode) to execute that
> instruction, and there are not many ocamlopt-generated programmes run
> in kernel mode... Maybe it is at a place which is not expected to be
> reached in "normal" programme execution (such as after a call to
> exit()). Are you sure this hlt comes from the ocamlopt generated code?
> 
> 
>>Perhaps ocaml 3.08.2 has some interesting bugs I'm not aware of?
> 
> 
> Actually, I'm working with version 3.08.3. But still, I would be
> interested if you found out the problem.

Re: [Caml-list] ocamlopt, and generated ASM

[Jonathan Roewen]

Nevermind. As always, I find the problem -after- mailing the list ;-)

On 7/27/05, Stephane Glondu <Stephane.Glondu@crans.org> wrote:
> Jonathan Roewen wrote:
> > I'm having some esoteric problems with my operating system project,
> > and it randomly halting (i.e.: the hlt instruction issued with
> > interrupts off). I've tried grepping the ocaml sources, but to no
> > avail.
> >
> > Could someone who has some in-depth knowledge of the code gneretor for
> > ocamlopt explain where these hlt instructions come from, and more
> > importantly, where abouts they are generated?
> 
> Where are these hlt exactly? In the asm file generated from the .ml
> file? In the startup code? In the runtime library? The string "hlt"
> doesn't seem to appear in ocaml (at least in version 3.08.3) source
> code, so it seems very weird (even though possible) that this
> instruction is generated by the compiler... Moreover, you usually need
> to be in privilege level 0 (in kernel mode) to execute that
> instruction, and there are not many ocamlopt-generated programmes run
> in kernel mode... Maybe it is at a place which is not expected to be
> reached in "normal" programme execution (such as after a call to
> exit()). Are you sure this hlt comes from the ocamlopt generated code?
> 
> > Perhaps ocaml 3.08.2 has some interesting bugs I'm not aware of?
> 
> Actually, I'm working with version 3.08.3. But still, I would be
> interested if you found out the problem.
> 
> 
> --
> 
> Stephane Glondu.
>