Re: [Xen-devel] apic probe of 2.6.32.41 pv linux

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Fri, 27 May 2011, Jiageng Yu wrote:
> 2011/5/27 Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>:
> > On Fri, May 27, 2011 at 05:58:51PM +0800, Jiageng Yu wrote:
> >> I have updated the pv linux kernel from 2.6.32.40 to 2.6.32.41. I
> >> found the generic_apic_probe always led to a kernel panic when I try
> >> to make the minimal DomU kernel.
> >>
> >> The 2.6.32.41 pv linux use the new apic probe mechanism:
> >
> > new..? What was it before?
> 
> 
> The linux kernel will invoke probe_default, which permanently returns 1.
> I wander to know may I just return 1 in 2.6.32.41 kernel? If there is
> no further problems.
> 

It seems to me that we have to return 1 unless CONFIG_X86_LOCAL_APIC is
disabled, and in that case we wouldn't need to set anything at all.
Considering that the default apic probe function will just return 1, I
suggest we just remove xen_safe_probe completely.
In fact we don't have it upstream.

Patch completely untested below:

---

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 0493093..0c31ceb 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -759,14 +759,6 @@ static __init int xen_safe_flat_acpi_madt_oem_check(char 
*oem_id,
        return 1;
 }
 
-static __init int xen_safe_probe(void) {
-
-       if (!xen_initial_domain())
-               return 0;
-
-       return 1;
-}
-
 struct apic apic_xen = {
        .name   = "xen",
 };
@@ -779,7 +771,6 @@ static __init void set_xen_basic_apic_ops(void)
        apic->icr_write = xen_apic_icr_write;
        apic->wait_icr_idle = xen_apic_wait_icr_idle;
        apic->safe_wait_icr_idle = xen_safe_apic_wait_icr_idle;
-       apic->probe = xen_safe_probe;
        apic->acpi_madt_oem_check  = xen_safe_flat_acpi_madt_oem_check;
        /* Copy over the full contents of the newly modified apic into
         * our apic_xen, which is to be called first by apic_probe[]. */

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