linux-kernel - Re: [PATCH v2] x86/io: Define readq()/writeq() to use 64-bit type

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Message-ID: <alpine.DEB.2.21.1805140910480.1582@nanos.tec.linutronix.de>
Date:   Mon, 14 May 2018 09:12:46 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        "H . Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] x86/io: Define readq()/writeq() to use 64-bit type

On Sun, 13 May 2018, Andy Shevchenko wrote:
> On Sun, May 13, 2018 at 9:09 PM, Thomas Gleixner <tglx@...utronix.de> wrote:
> > On Thu, 3 May 2018, Andy Shevchenko wrote:
> >>  #ifdef CONFIG_X86_64
> >>
> >> -build_mmio_read(readq, "q", unsigned long, "=r", :"memory")
> >> -build_mmio_read(__readq, "q", unsigned long, "=r", )
> >> -build_mmio_write(writeq, "q", unsigned long, "r", :"memory")
> >> -build_mmio_write(__writeq, "q", unsigned long, "r", )
> >> +build_mmio_read(readq, "q", unsigned long long, "=r", :"memory")
> >> +build_mmio_read(__readq, "q", unsigned long long, "=r", )
> >> +build_mmio_write(writeq, "q", unsigned long long, "r", :"memory")
> >> +build_mmio_write(__writeq, "q", unsigned long long, "r", )
> >
> > What's wrong with u64 which we use for expressing io access to a 64bit wide
> > resource?
> 
> Same answer as per v1, i.e. I would like to be consistent with other
> types in this file (unsigned int for readl() and similar for the
> rest).
> If we would need them, we might change at once for all accessors.

I don;t think we need to fixup everything in one go. Having the patch which
addresses the issue at hand first using u64 makes a lot of sense on its own.

Changing the other instances can be done as a follow up patch. Having
explicit with types for such kind of accessors makes a lot of sense.

Thanks,

	tglx