Re: [PATCH v2 1/4] x86/boot: print CPU and APIC ID in bring up failure

["Roger Pau Monné" <roger.pau@citrix.com>]

On Thu, May 22, 2025 at 06:22:19PM +0100, Andrew Cooper wrote:
> On 22/05/2025 5:50 pm, Roger Pau Monné wrote:
> > On Thu, May 22, 2025 at 03:39:57PM +0100, Andrew Cooper wrote:
> >> On 22/05/2025 10:10 am, Jan Beulich wrote:
> >>> On 22.05.2025 09:54, Roger Pau Monne wrote:
> >>>> Print the CPU and APIC ID that fails to respond to the init sequence, or
> >>>> that didn't manage to reach the "callin" state.  Expand a bit the printed
> >>>> error messages.  Otherwise the "Not responding." message is not easy to
> >>>> understand by users.
> >>>>
> >>>> Reported-by: Andrew Cooper <andrew.cooper3@citrix.com>
> >>>> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
> >>>> ---
> >>>> Changes since v1:
> >>>>  - Also print APIC ID.
> >>>> ---
> >>>>  xen/arch/x86/smpboot.c | 6 ++++--
> >>>>  1 file changed, 4 insertions(+), 2 deletions(-)
> >>>>
> >>>> diff --git a/xen/arch/x86/smpboot.c b/xen/arch/x86/smpboot.c
> >>>> index 0189d6c332a4..dbc2f2f1d411 100644
> >>>> --- a/xen/arch/x86/smpboot.c
> >>>> +++ b/xen/arch/x86/smpboot.c
> >>>> @@ -618,10 +618,12 @@ static int do_boot_cpu(int apicid, int cpu)
> >>>>              smp_mb();
> >>>>              if ( bootsym(trampoline_cpu_started) == 0xA5 )
> >>>>                  /* trampoline started but...? */
> >>>> -                printk("Stuck ??\n");
> >>>> +                printk("CPU%u/APICID%u: Didn't finish startup sequence\n",
> >>>> +                       cpu, apicid);
> >>>>              else
> >>>>                  /* trampoline code not run */
> >>>> -                printk("Not responding.\n");
> >>>> +                printk("CPU%u/APICID%u: Not responding to startup\n",
> >>>> +                       cpu, apicid);
> >>>>          }
> >>>>      }
> >>>>  
> >>> Elsewhere I think we print AIC IDs in hex; may be better to do so here, too.
> >>> That may then want some text re-arrangement though, e.g.
> >>>
> >>> "CPU%u: APICID %#x not responding to startup\n"
> >>>
> >>> Thoughts?
> >> Definitely hex.  Elsewhere APIC_ID always has an underscore.
> > Maybe I'm confused, but I don't think Xen uses an underscore, it's
> > always 'APIC ID' when printed.  I don't mind adding it here, I assume
> > what you mean with elsewhere is other projects like Linux?
> 
> It's apic_id in plenty of smpboot.c, but fine - lets do it with a space.
> 
> We do need to reduce from $N ways of rendering this down to 1.

Oh, so it's lowercase with underscore.  Anyway, will use uppercase and
space as agreed.

Thanks, Roger.