[RFC PATCH 13/14] ARM: vexpress: Definition of vexpress dts specification

[M. Warner Losh]

In message: <AANLkTi=WiHd06=e4d_WdCe+HMfFhj-Q=xRS_4f-TzGUs at mail.gmail.com>
            Grant Likely <grant.likely at secretlab.ca> writes:
: Regardless though, the linux mapping doesn't actually have any bearing
: on the device tree because the mapping from HW to linux irq number is
: all internal to the kernel.  The kernel could choose to start the
: mapping at 42 or somewhere else and it would all still work.

Some (all?) PowerPC platforms start their interrupt numbering at 16,
since interrupts 0-15 are reserved for old-school ISA interrupts from
the Super I/O chip that may (or may not) be present on these systems.
It's all handled inside the kernel, so is invisible to the
device-tree, as Grant is saying.  Also, more OSes than Linux use
device trees, so hard-coding Linux IRQ numbers would be displeasing
from that point of view.

Just to give one concrete example.

Warner