linux-kernel - Re: how to fix acpi_pci_root_remap

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Date:   Fri, 17 Aug 2018 18:20:03 +0200
From:   Boris Brezillon <boris.brezillon@...tlin.com>
To:     "Luck, Tony" <tony.luck@...el.com>
Cc:     Arnd Bergmann <arnd@...db.de>, Bjorn Helgaas <bhelgaas@...gle.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "jchandra@...adcom.com" <jchandra@...adcom.com>,
        Sinan Kaya <okaya@...eaurora.org>,
        Tomasz Nowicki <tn@...ihalf.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        "Miquel Raynal" <miquel.raynal@...tlin.com>
Subject: Re: how to fix acpi_pci_root_remap_iospace?

On Fri, 17 Aug 2018 15:56:23 +0000
"Luck, Tony" <tony.luck@...el.com> 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.

> 
> > Hm, maybe it's just easier to revert the patch since we got rid of
> > patches adding COMPILE_TEST to drivers which were using read/writesl()
> > (it turned out ia64 and sparc were not the only archs to not implement
> > readsx/writesx() variants, and fixing them is not that easy).  
> 
> That sounds like a better course of action.

The solution I propose here is just a way to get that problem fixed
quickly, but I'd still like to have a way to enable the s3c2xx and
orion NAND driver when COMPILE_TEST=y.