Re: [patch RFC 30/38] PCI/MSI: Allow to disable arch fallbacks

Bjorn Helgaas
2020-08-25T21:35:05Z

On Tue, Aug 25, 2020 at 11:28:30PM +0200, Thomas Gleixner wrote:
> On Tue, Aug 25 2020 at 15:07, Bjorn Helgaas wrote:
> >> + * The arch hooks to setup up msi irqs. Default functions are implemented
> >> + * as weak symbols so that they /can/ be overriden by architecture specific
> >> + * code if needed.
> >> + *
> >> + * They can be replaced by stubs with warnings via
> >> + * CONFIG_PCI_MSI_DISABLE_ARCH_FALLBACKS when the architecture fully
> >> + * utilizes direct irqdomain based setup.

> > If not, it seems like it'd be nicer to have the burden on the arches
> > that need/want to use arch-specific code instead of on the arches that
> > do things generically.
>
> Right, but they still share the common code there and some of them
> provide only parts of the weak callbacks. I'm not sure whether it's a
> good idea to copy all of this into each affected architecture.
>
> Or did you just mean that those architectures should select
> CONFIG_I_WANT_THE CRUFT instead of opting out on the fully irq domain
> based ones?

Yes, that was my real question -- can we confine the cruft in the
crufty arches? If not, no big deal.

Bjorn