On Mon, Feb 16, 2015 at 03:21:04PM +0100, Koop Mast wrote:
> On 9-2-2015 22:00, Konstantin Belousov wrote:
> > Author: kib
> > Date: Mon Feb  9 21:00:56 2015
> > New Revision: 278473
> > URL: https://svnweb.freebsd.org/changeset/base/278473
> >
> > Log:
> >    Add x2APIC support.  Enable it by default if CPU is capable.  The
> >    hw.x2apic_enable tunable allows disabling it from the loader prompt.
> 
> Hi Konstantin,
> 
> This commit broke my Sandybridge laptop. If x2APIC is enabled the kernel 
> freezes after the
> "ACPI APIC Table: <_ASUS_ NoteBook>" line is printed. I can't get much 
> information out of it since I couldn't get into the kernel debugger nor 
> has the machine a serial cable.
Can you provide e.g. a photo of the machine screen with the hang boot,
of the same kernel you used for the dmesg log below ?

Also, please provide the output of acpidump -t.

> 
> I did notice that "x2APIC" is listed in the CPU Features2 list, but for 
> the cpu's it reports "x2APIC: 0". I don't know if this has to do with 
> disabled x2APIC or some hardware/bios issue?
x2APIC tag for the LAPIC reports appear when cpu declares support for
x2APIC mode, like in your case.  The 0/1 indicates the final value used
by kernel, i.e. 0 means disabled, by user override (your case), by BIOS
request, or due to detection of incompatible hypervisor.

> 
> -Koop
> 
> Verbose dmesg with x2APIC disabled: 
> https://people.freebsd.org/~kwm/dmesg-x2apic.txt

Also, please try the following patch.  Only the local_apic.c chunk could
matter for you.

diff --git a/sys/amd64/amd64/mp_machdep.c b/sys/amd64/amd64/mp_machdep.c
index 13c3d43..b767691 100644
--- a/sys/amd64/amd64/mp_machdep.c
+++ b/sys/amd64/amd64/mp_machdep.c
@@ -1507,6 +1507,7 @@ cpususpend_handler(void)
                vmm_resume_p();
 
        /* Resume MCA and local APIC */
+       lapic_xapic_mode();
        mca_resume();
        lapic_setup(0);
 
diff --git a/sys/i386/i386/mp_machdep.c b/sys/i386/i386/mp_machdep.c
index 32b9540..a80de54 100644
--- a/sys/i386/i386/mp_machdep.c
+++ b/sys/i386/i386/mp_machdep.c
@@ -1555,6 +1555,7 @@ cpususpend_handler(void)
                cpu_ops.cpu_resume();
 
        /* Resume MCA and local APIC */
+       lapic_xapic_mode();
        mca_resume();
        lapic_setup(0);
 
diff --git a/sys/x86/acpica/acpi_wakeup.c b/sys/x86/acpica/acpi_wakeup.c
index 74522be..e652419 100644
--- a/sys/x86/acpica/acpi_wakeup.c
+++ b/sys/x86/acpica/acpi_wakeup.c
@@ -270,6 +270,7 @@ acpi_wakeup_machdep(struct acpi_softc *sc, int state, int 
sleep_result,
                        initializecpu();
                        PCPU_SET(switchtime, 0);
                        PCPU_SET(switchticks, ticks);
+                       lapic_xapic_mode();
 #ifdef SMP
                        if (!CPU_EMPTY(&suspcpus))
                                acpi_wakeup_cpus(sc);
diff --git a/sys/x86/x86/local_apic.c b/sys/x86/x86/local_apic.c
index 1809fa6..1b66674 100644
--- a/sys/x86/x86/local_apic.c
+++ b/sys/x86/x86/local_apic.c
@@ -527,7 +527,6 @@ native_lapic_xapic_mode(void)
        saveintr = intr_disable();
        if (x2apic_mode)
                native_lapic_enable_x2apic();
-       native_lapic_disable();
        intr_restore(saveintr);
 }
 
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