Re: [PATCH] Longhaul - There are limits

[Dave Jones <davej@redhat.com>]

On Mon, Jul 03, 2006 at 06:00:07PM +0200, Rafał Bilski wrote:

 > > It's not unfeasible for an SMP kernel to be run on UP hardware,
 > > (and several distros are shipping SMP kernels as default)
 > > so I'm in two minds about removing the !SMP check, and making it be a
 > > 
 > > 	if (num_online_cpus() > 1)
 > > 		return -ENODEV;
 > > 
 > > in the init routine.
 > > 
 > > Thoughts?
 > > 
 > > 		Dave
 > > 
 > 
 > It is good idea, but I think there should be check for APIC too, 
 > but I don't know how to make it. !X86_UP_APIC is for non SMP 
 > kernels only. It is possible that in this case there will be 
 > SMP kernel running on single processor with APIC enabled. 
 > I don't know much about APIC, but as far I know we are poking 
 > PIC registers direcly and in such case not all interrupts will
 > be disabled.

I wonder if this could be solved with something as trivial as..

	if (cpu_has_apic)
		disable_local_APIC()

	...

	if (cpu_has_apic)
		enable_local_APIC()

We should probably also avoid touching the PIC if we're in APIC mode
with something like..

    if (pic_mode == 1) {
		...
		PIC poking goes here..
	}

(Will also need to EXPORT_SYMBOL(pic_mode) from mpparse.c)

		Dave

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