On 12/06/14 09:37, Linus Walleij wrote:

On Thu, Jun 5, 2014 at 11:53 AM, Daniel Thompson
[off-list ref] wrote:

quoted

Currently enable_fiq/disable_fiq use a simple offset to convert an IRQ
virq into a FIQ virq. This is too inflexible for multi-platform kernels
and makes runtime error checking impossible.

We solve this by introducing a flexible mapping that allows interrupt
controllers that support FIQ to register those mappings. This, in turn,
makes it much possible for drivers in DT kernels to gain access to
FIQ virqs.

I always had a big problem with the term "virq" which I take to mean
"virtual IRQ".

So do I...

That said, I think of it as the virtual as in virtual memory rather the
virtual contained within virtualization.

The distinction is:

- Hardware IRQ offsets/numbers - a number encoded in HW
  specs which we usually call hwirqs

- Linux IRQ numbers - just some number

Sometimes, just sometimes, the Linux IRQ number matches the
HW numbers, and then I guess the IRQ is regarded "non-virtual".
The only real effect being that the numbers shown in
/proc/interrupts are the same in both columns... the leftmost
column with the Linux IRQ number and the one right next to
the IRQ controller name which is the hwirq local offset.

But all Linux IRQ numbers are virtual by definition. It's just some
number that the kernel use as a cookie to look up the irq_desc.
And one day we may get rid of IRQ numbers altogether.

I would prefer just to s/virq/irq/g on this patch or if that is
disturbing something more to the point like s/virq/linux_irq/g.

Maybe this is a pointless battle, but still...

I chose the term not because I have a personal attachement but because
that is how they are spelt in the C symbols within irqdomain.[ch] which
my patch relies upon heavily. The english documentation and comments is
(very nearly) strict about using "Linux IRQ" so I'll happily change all
the English text.

However...

I don't fancy s/virq/irq/ since this risks confusion between Linux irq
and ARM IRQ and I don't fancy s/virq/linux_irq/ because in the kernel
today virq is ~750x more frequenctly used than 'linux_irq' (git grep and
wc suggests its 1507 versus 2).

How strongly do you feel about this?