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Subject: Re: Boot crash with 659006b x86/x2apic: Split enable and setup
 function
To: Thomas Gleixner <tglx@linutronix.de>
References: <55C75AEB.4070703@redhat.com>
Cc: Jiang Liu <jiang.liu@linux.intel.com>, Joerg Roedel <joro@8bytes.org>,
        Tony Luck <tony.luck@intel.com>, Borislav Petkov <bp@alien8.de>,
        javiermon@gmail.com, x86@kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
From: Laura Abbott <labbott@redhat.com>
Message-ID: <55C75CDD.5080109@redhat.com>
Date: Sun, 9 Aug 2015 06:59:57 -0700
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(missed the LKML cc apologies for the noise)

On 08/09/2015 06:51 AM, Laura Abbott wrote:
> Hi,
>
> We received a report[1] of an early boot crash. The reporter had difficulty getting a full
> kernel log to view and only had a screenshot which showed a crash in native_apic_mem_read
> (full screenshot available at the bugzilla along with dmesg from working kernel)
>
>   Bisection identified the following commit:
>
> commit 659006bf3ae37a08706907ce1a36ddf57c9131d2
> Author: Thomas Gleixner <tglx@linutronix.de>
> Date:   Thu Jan 15 21:22:26 2015 +0000
>
>      x86/x2apic: Split enable and setup function
>
>      enable_x2apic() is a convoluted unreadable mess because it is used for
>      both enablement in early boot and for setup in cpu_init().
>
>      Split the code into x2apic_enable() for enablement and x2apic_setup()
>      for setup of (secondary cpus). Make use of the new state tracking to
>      simplify the logic.
>
>      Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
>      Cc: Jiang Liu <jiang.liu@linux.intel.com>
>      Cc: Joerg Roedel <joro@8bytes.org>
>      Cc: Tony Luck <tony.luck@intel.com>
>      Cc: Borislav Petkov <bp@alien8.de>
>      Link: http://lkml.kernel.org/r/20150115211703.129287153@linutronix.de
>      Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
>
> The report indicates that if local x2apic is disabled in the BIOS the kernel boots.
>
> Any ideas?
>
> Thanks,
> Laura
>
> [1]https://bugzilla.redhat.com/show_bug.cgi?id=1224764