Re: [Xen-devel] [PATCH v2 4/8] xen: Use the correctly the Xen memory terminologies

[Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>]

On Wed, Aug 05, 2015 at 11:08:55AM +0100, Stefano Stabellini wrote:
> On Tue, 4 Aug 2015, Julien Grall wrote:
> > Based on include/xen/mm.h [1], Linux is mistakenly using MFN when GFN
> > is meant, I suspect this is because the first support for Xen was for
> > PV. This resulted in some misimplementation of helpers on ARM and
> > confused developers about the expected behavior.
> > 
> > For instance, with pfn_to_mfn, we expect to get an MFN based on the name.
> > Although, if we look at the implementation on x86, it's returning a GFN.
> > 
> > For clarity and avoid new confusion, replace any reference to mfn with
> > gfn in any helpers used by PV drivers. The x86 code will still keep some
> > reference of pfn_to_mfn but exclusively for PV (a BUG_ON has been added
> > to ensure this). No changes as been made in the hypercall field, even
> > though they may be invalid, in order to keep the same as the defintion
> > in xen repo.
> > 
> > Take also the opportunity to simplify simple construction such
> > as pfn_to_mfn(page_to_pfn(page)) into page_to_gfn. More complex clean up
> > will come in follow-up patches.
> > 
> > [1] 
> > http://xenbits.xen.org/gitweb/?p=xen.git;a=commitdiff;h=e758ed14f390342513405dd766e874934573e6cb
> > 
> > Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
> > Cc: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> > Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
> > Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> > Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
> > Cc: David Vrabel <david.vrabel@xxxxxxxxxx>
> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> > Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> > Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
> > Cc: x86@xxxxxxxxxx
> > Cc: "Roger Pau Monné" <roger.pau@xxxxxxxxxx>
> > Cc: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
> > Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
> > Cc: Juergen Gross <jgross@xxxxxxxx>
> > Cc: "James E.J. Bottomley" <JBottomley@xxxxxxxx>
> > Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > Cc: Jiri Slaby <jslaby@xxxxxxxx>
> > Cc: Jean-Christophe Plagniol-Villard <plagnioj@xxxxxxxxxxxx>
> > Cc: Tomi Valkeinen <tomi.valkeinen@xxxxxx>
> > Cc: linux-input@xxxxxxxxxxxxxxx
> > Cc: netdev@xxxxxxxxxxxxxxx
> > Cc: linux-scsi@xxxxxxxxxxxxxxx
> > Cc: linuxppc-dev@xxxxxxxxxxxxxxxx
> > Cc: linux-fbdev@xxxxxxxxxxxxxxx
> > Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> 
> Aside from the x86 bits:
> 
> Reviewed-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>

Not really important, but just in case anyone waits for my ack on input
bits:

Acked-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>

Thanks.

-- 
Dmitry

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