FPU state management in L4Fiasco.OC program

Mai, Haohui haohui.mai at gmail.com
Tue Apr 17 00:34:05 CEST 2012


Hi,

I think alien is still essential since I plan to run Linux binary directly
on top of my OS, thus I don't really want them to call L4 API directly.

If alien thread is required, what would be the best way of doing it?

~Haohui

On Mon, Apr 16, 2012 at 5:25 PM, Adam Lackorzynski <
adam at os.inf.tu-dresden.de> wrote:

>
> On Fri Apr 13, 2012 at 13:33:54 -0500, Mai, Haohui wrote:
> > Adam,
> >
> > Thanks for your clarification.
> >
> > One thing that I'm not still quite clear is that how to manage FPU
> context
> > in my settings.
> >
> > The main challenge here is that to keep track the "current" pointer
> > (similar to the current pointer in L4Linux) -- otherwise it's difficult
> to
> > save the FPU context.
> >
> > My OS only handles page faults and syscalls, and delegates scheduling
> > processes to L4 completely.
> >
> > Handling page faults and syscalls is easy in the sense that the IPC
> > messages have complete information.
> >
> > However, It's not immediately clear to me that how to keep track of
> > "current" pointer and to save / restore FPU context.
> >
> > Do you have any comments on this one? I appreciate your help.
>
> Ok, then the question actually is why your user processes are running as
> aliens at all. Receiving page-faults and other exceptions does not
> depend on being an alien. This also works without it. Then the kernel
> would just handle the FPU transparently for the threads and your handler
> thread does not need to care about that.
>
>
> Adam
> --
> Adam                 adam at os.inf.tu-dresden.de
>  Lackorzynski         http://os.inf.tu-dresden.de/~adam/
>
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