Re: [Xen-ia64-devel] Why is cpl read as 0 in para-virtualization ?

[Tristan Gingold <Tristan.Gingold@xxxxxxxx>]

Le Mercredi 01 Mars 2006 16:44, Magenheimer, Dan (HP Labs Fort Collins) a 
écrit :
> > Subject: [Xen-ia64-devel] Why is cpl read as 0 in
> > para-virtualization ?
> >
> > while I was modifying xen_early_setup, I tried to replace dcr
> > kludge using
> > cpl.  Unfortunatly, it doesn't work since cpl is read as 0
> > (see vcpu.c).
> > So my question is simple: why ?
>
> I think some places in Linux/ia64 determine whether code
> is running in kernel or user mode by checking psr.cpl.
Correct.
One place is user_mode() is ptrace.h.
Currently it is true if cpl != 0.  I have made a simple test: I have changed 
the code to cpl == 3, and cpl reads as 2.  Linux is booting (dom0+domU).

Tristan.


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