On Saturday, June 07, 2014 4:47:39 am Edward Tomasz Napierała wrote:
> On 0604T1036, John Baldwin wrote:
> > On Monday, June 02, 2014 5:32:13 pm Edward Tomasz Napierała wrote:
> > > Some machines, including ThinkPad T61, emit the following error message
> > > early during boot:
> > > 
> > > CPU0: local APIC error 0x40
> > > 
> > > The message itself doesn't seem to be much of a problem.  However,
> > > every once in a while booting hangs just before that line.  I've tracked
> > > that down to call to AcpiHwWritePort() at
> > > sys/contrib/dev/acpica/components/hardware/hwacpi.c:117:
> > > 
> > >     switch (Mode)
> > >     {
> > >     case ACPI_SYS_MODE_ACPI:
> > > 
> > >         /* BIOS should have disabled ALL fixed and GP events */
> > > 
> > >         Status = AcpiHwWritePort (AcpiGbl_FADT.SmiCommand,
> > >                         (UINT32) AcpiGbl_FADT.AcpiEnable, 8);
> > > 
> > > Any idea what might be going on?
> > 
> > This is probably triggering an SMI# to enter SMM mode where your BIOS does 
> > God-knows-what but apparently triggers one of the local APIC local 
> > interrupts 
> > while it is configured with an invalid vector (e.g. 0).
> 
> Is there anything that can be done to fix it?  (Note that fixing the
> suspend/resume seems to have also fixed the occasional hang on boot,
> but perhaps it's because I don't need to boot this thing so often now.)

Likely not.  This is actually the magic command to tell the BIOS that the OS
is ACPI-aware and to ask the BIOS to enable ACPI support.  It can do all sorts
of things and is completely outside of OS control while it runs.  The local
APIC thing is logged when the OS gains control again, but it's harmless.

-- 
John Baldwin
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