EARLY_AP_STARTUP hangs during boot

[Konstantin Belousov]

On Mon, May 16, 2016 at 12:27:31PM +0200, Gary Jennejohn wrote:
> On Mon, 16 May 2016 12:22:42 +0200
> Gary Jennejohn <gljennjohn at gmail.com> wrote:
> 
> > I tried out EARLY_AP_STARTUP, but the kernel hangs and I can't
> > break into DDB.
> > 
> > I did a verbose boot and the last lines I see are related to routing
> > MSI-X to various local APIC vectors.  I copied the last few lines and
> > they look like this:
> > 
> > msi: routing MSI-X IRQ 256 to local APIC 2 vector 48
> > msi: routing MSI-X IRQ 257 to local APIC 3 vector 48
> > msi: routing MSI-X IRQ 258 to local APIC 4 vector 48
> > msi: routing MSI-X IRQ 256 to local APIC 0 vector 49
> 
> Oops, the the last line should read
> msi: Assigning MSI-X IRQ 256 to local APIC 0 vector 49
You should be able to enter ddb at this point. Methods depend on the
console used, serial break for serial console, ctrl-alt-esc for sc/vt
AFAIR. If you have IPMI/DRAC/ILO, send nmi.

After getting at ddb> prompt, do 'bt' then 'ps' then 'alltrace' and
show the output.