Re: IRQ domain logging?

[Thomas Gleixner <tglx@linutronix.de>]

On Wed, Apr 23 2025 at 10:23, Lukas Wunner wrote:
> On Tue, Apr 22, 2025 at 04:07:05PM -0500, Bjorn Helgaas wrote:
>> This from an arm64 system is even more obscure to me:
>> 
>>   NR_IRQS: 64, nr_irqs: 64, preallocated irqs: 0
>>   GICv3: 256 SPIs implemented
>>   Root IRQ handler: gic_handle_irq
>>   GICv3: GICv3 features: 16 PPIs
>>   kvm [1]: vgic interrupt IRQ18
>>   xhci-hcd xhci-hcd.0.auto: irq 67, io mem 0xfe800000
>> 
>> I have no clue where irq 67 goes.
>
> There's quite a bit of information available in /proc/interrupts,
> /proc/irq/ and /sys/kernel/irq/, I guess that's what most people use.

/sys/kernel/debug/irq/....

Gives the most comprehensive insight into the domain hierarchy.

# cat /sys/kernel/debug/irq/irqs/204
handler:  handle_edge_irq
device:   0000:01:00.0
status:   0x00000000
istate:   0x00004000
ddepth:   0
wdepth:   0
dstate:   0x1d401200
            IRQD_ACTIVATED
            IRQD_IRQ_STARTED
            IRQD_SINGLE_TARGET
            IRQD_AFFINITY_SET
            IRQD_AFFINITY_ON_ACTIVATE
            IRQD_CAN_RESERVE
            IRQD_HANDLE_ENFORCE_IRQCTX
node:     0
affinity: 50
effectiv: 50
pending:  
domain:  PCI-MSIX-0000:01:00.0-12
 hwirq:   0x65
 chip:    PCI-MSIX-0000:01:00.0
  flags:   0x1430
             IRQCHIP_SKIP_SET_WAKE
             IRQCHIP_ONESHOT_SAFE
             IRQCHIP_MOVE_DEFERRED

  address_hi: 0x00000000
  address_lo: 0xfee32000
  msg_data:   0x00000023
 parent:
    domain:  VECTOR
     hwirq:   0xcc
     chip:    APIC
      flags:   0x0
     Vector:    35
     Target:    50
     move_in_progress: 0
     is_managed:       0
     can_reserve:      1
     has_reserved:     0
     cleanup_pending:  0

It shows the complete domain hierarchy for each interrupt an
irq/domains/.... gives extra information about the domains.

You need to enable GENERIC_IRQ_DEBUGFS.

Exposing this in dmesg in a comprehensible and condensed form might be
possible, but needs some thought.

So far I survived pretty good with the debugfs data.

Thanks,

        tglx