linux-kernel - Re: Question Regarding ERMS memcpy

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Message-ID: <20170306140002.ilw3bpzpm3xzf5pk@pd.tnic>
Date:   Mon, 6 Mar 2017 15:00:02 +0100
From:   Borislav Petkov <bp@...e.de>
To:     hpa@...or.com
Cc:     Logan Gunthorpe <logang@...tatee.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Tony Luck <tony.luck@...el.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        the arch/x86 maintainers <x86@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Question Regarding ERMS memcpy

On Mon, Mar 06, 2017 at 05:41:22AM -0800, hpa@...or.com wrote:
> It isn't really that straightforward IMO.
>
> For UC memory transaction size really needs to be specified explicitly
> at all times and should be part of the API, rather than implicit.
>
> For WC/WT/WB device memory, the ordinary memcpy is valid and
> preferred.

I'm practically partially reverting

6175ddf06b61 ("x86: Clean up mem*io functions.")

Are you saying, this was wrong before too?

Maybe it was wrong, strictly speaking, but maybe that was good enough
for our purposes...

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--