Re: how to fix acpi_pci_root_remap_iospace?

From: Arnd Bergmann
Date: Fri Aug 17 2018 - 15:01:28 EST

On Fri, Aug 17, 2018 at 6:20 PM Boris Brezillon
<boris.brezillon@xxxxxxxxxxx> wrote:
> On Fri, 17 Aug 2018 15:56:23 +0000
> "Luck, Tony" <tony.luck@xxxxxxxxx> wrote:
> > >> - Some targets don't have any support for I/O space on their PCI bus and just
> > >> want to get things to compile by setting PCI_IOBASE to zero, this still opens
> > >> up some of the same problems as above, but doesn't really help otherwise.
> >
> > That sounds horrible. Why would you want to have a driver that can't possibly
> > work on your platform compile cleanly? That's just asking for trouble. Sombody
> > might load that driver, and ... all the outb/outw/outl calls just corrupt low memory.
> Well, COMPILE_TEST is here just for that, and it's actually quite
> useful to detect potential compilation errors/warnings and make sure
> the driver is portable. So, either we decide that readsx/writesx() are
> not standard and we create a Kconfig option to reflect when an arch
> implements them so that drivers using those funcs can at least be
> compile-tested on a few archs, or we fix all archs that do not
> implement those functions.

What I meant is not specifically for compile testing, but for drivers
that are used and required on regular platforms and can be used with
either MMIO or PIO mode. serial_8250 is the typical example here,
but there are others as well.