irqdomain: Let irq_domain_mapping display hierarchical domains
authorMarc Zyngier <marc.zyngier@arm.com>
Fri, 12 May 2017 11:55:35 +0000 (12:55 +0100)
committerThomas Gleixner <tglx@linutronix.de>
Mon, 22 May 2017 20:29:44 +0000 (22:29 +0200)
commitfe17a42e704a64477b15bb2cf8366fe3e5119aff
tree6770615193f7245cefc49a873baa1d9345b4bd69
parent08332893e37af6ae779367e78e444f8f9571511d
irqdomain: Let irq_domain_mapping display hierarchical domains

Hierarchical domains seem to be hard to grasp, and a number of
aspiring kernel hackers find them utterly discombobulating.

In order to ease their pain, let's make them appear in
/sys/kernel/debug/irq_domain_mapping, such as the following:

   96  0x81808  MSI    0x          (null) RADIX   MSI
   96+ 0x00063  GICv2m 0xffff8003ee116980 RADIX   GICv2m
   96+ 0x00063  GICv2  0xffff00000916bfd8 LINEAR  GICv2

[output compressed to fit in a commit log]

This shows that IRQ96 is implemented by a stack of three domains,
the + sign indicating the stacking.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Link: http://lkml.kernel.org/r/20170512115538.10767-2-marc.zyngier@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
kernel/irq/irqdomain.c