Re: [PATCH] Revert "x86/apic: Remove init_bsp_APIC()"

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Nov 30, 2017 at 02:28:18PM +0800, Dou Liyang wrote:
> Hi, Ville
> 
> At 11/30/2017 05:25 AM, Ville Syrjälä wrote:
> > On Wed, Nov 29, 2017 at 09:15:19AM +0800, Dou Liyang wrote:
> >> Hi Ville,
> >>
> >> At 11/28/2017 10:53 PM, Ville Syrjala wrote:
> >>> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >>>
> >>> This reverts commit b371ae0d4a194b178817b0edfb6a7395c7aec37a.
> >>>
> >>> Causes my P3 UP machine to hang at boot with "lapic".
> >>>
> >>> Cc: Dou Liyang <douly.fnst@cn.fujitsu.com>
> >>> Cc: Thomas Gleixner <tglx@linutronix.de>
> >>> Cc: yinghai@kernel.org
> >>> Cc: bhe@redhat.com
> >>> Cc: Ingo Molnar <mingo@redhat.com>
> >>> Cc: "H. Peter Anvin" <hpa@zytor.com>
> >>> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >>> ---
> >>
> >> Could you give me the dmesg log of your P3 UP machine?
> >
> > This is with the revert:
> 
> Oops, Sorry about my ambiguous description, I knew the revert patch
> could work.
> 
> Actually, It's an interesting problem. your machine (UP system without
> ACPI table and MP table) will make the interrupt mode in a rare
> situation:
> 
>    Virtual Wire Mode with no configuration
> 
> My test cases also simulate this situation, can work well. I hope to
> know why you machine hang?
> 
> So, the true thing I want to get is the log without the revert.
> or could you tell me the phenomenon and reason of your machine hang
> directly. :-)

IIRC the last thing in the log is the "Hierarchical SRCU implementation."
line, after which the CPU seems to start spinning somewhere (the fan turns
on pretty quickly). Where exactly it spins, I don't know at this time.

-- 
Ville Syrjälä
Intel OTC