On Sun, 2006-10-08 at 10:13 +0800, Zou, Nanhai wrote:
> > -----Original Message-----
> > From: Khalid Aziz [mailto:[EMAIL PROTECTED]
> > Sent: 2006年10月2日 23:33
> > To: Horms
> > Cc: Zou, Nanhai; Fastboot mailing list
> > Subject: Re: [Fastboot] kexec_fake_sal_rendez broken?
> >
> > On Mon, 2006-10-02 at 17:29 +0900, Horms wrote:
> > > Hi Nanhai,
> > >
> > > I have been looking a little into kexec_fake_sal_rendez,
> > > as I think that kexec for xen will need to use it as I don't
> > > believe that any CPU hotplug infastructure is present there.
> > >
> > > Unfortunately, when compile linux without CPU hotplug support -
> > > thus forcing the kexec_fake_sal_rendez method of shutting down CPUs
> > > to be used - kexec no longer functions unless I set maxcpus=1 when
> > > kexecing into the second kernel.
> > >
> > > Is this a problem that you are aware of?
> > > Do you have any idea where I should poke around to fix it?
> > >
> >
> > That code has not caused problems on single cpu machine in the past. I
> > will take a look.
> >
>
>
> Hi Aziz,
> I think calling to the fake_rendz code need to be relocated to control
> page.
> Otherwise there will be problem if kexec into a different kernel. New kernel
> may overlap to the area of fake_rendz code linked in first kernel.
>
> Thanks
> Zou Nan hai
Hi Nan hai,
kexec_fake_sal_rendez is already on control page. Are you suggesting we
move kexec_stop_this_cpu() as well to control page? Theoretically since
we call smp_call_function() with wait=0, it is possible that monarch
might start copying new kernel over before other procesors have had a
chance to process IPI and execute kexec_stop_this_cpu(). In such a case,
there is a possibility kexec_stop_this_cpu() code might be overwritten
with something else before execution. The only right way I can think of
to solve this is to establish a handshake between monarch and slave
processors so monarch can ensure all slave processors have stopped
before it starts copying new kernel over. We could instead call
smp_call_function() with wait=1, but that somehow makes me nervous.
--
Khalid
====================================================================
Khalid Aziz Open Source and Linux Organization
(970)898-9214 Hewlett-Packard
[EMAIL PROTECTED] Fort Collins, CO
"The Linux kernel is subject to relentless development"
- Alessandro Rubini
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