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

[Jan Beulich <jbeulich@xxxxxxxx>]

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@xxxxxxxxxx>
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> ---
> 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?

Jan