Re: [Xen-devel] [PATCH 5/7] xen/iommu: smmu-v3: Add Xen specific code to enable the ported driver

[Julien Grall <julien.grall@xxxxxxx>]

Hi Jan,

On 01/03/18 14:21, Jan Beulich wrote:
> > > > On 01.03.18 at 15:07, <julien.grall@xxxxxxx> wrote:
> > On 09/02/18 03:10, Sameer Goel wrote:
> > > This driver follows an approach similar to smmu driver. The intent here
> > > is to reuse as much Linux code as possible.
> > > - Glue code has been introduced to bridge the API calls.
> > > - Called Linux functions from the Xen IOMMU function calls.
> > > - Xen modifications are preceded by /*Xen: comment */
> > > - xen/linux_compat: Add a Linux compat header
> > >     For porting files directly from Linux it is useful to have a function 
> > > mapping
> > >     definitions from Linux to Xen. This file adds common API functions and
> > >     other defines that are needed for porting arm SMMU drivers.
> > I understand Roger asked for it, but that was not a really wise choice
> > given the size of this patch. Anyway, let's keep it like that.
> >
> > > Signed-off-by: Sameer Goel <sameer.goel@xxxxxxxxxx>
> > > ---
> > >    xen/arch/arm/p2m.c                    |   1 +
> > >    xen/drivers/Kconfig                   |   2 +
> > >    xen/drivers/passthrough/arm/Kconfig   |   8 +
> > >    xen/drivers/passthrough/arm/Makefile  |   1 +
> > >    xen/drivers/passthrough/arm/smmu-v3.c | 892 
> > > ++++++++++++++++++++++++++++++++--
> > >    xen/include/xen/linux_compat.h        |  84 ++++
> > You need to CC the REST maintainers for that.
> And to be honest, I find adding such disgusting. We've imported
> _lots_ of stuff from Linux, yet never needed things like gfp
> definitions. I'm far from convinced that converting the new file
> in at least some basic aspects to "Xen wording" would complicate
> maintaining that file significantly. Headers included at the top
> obviously can't use linux/ anyway, so it's never going to be a
> verbatim copy.
What Sameer has been doing for SMMUv3 is following the word we did on 
the ARM SMMUv2 driver. The header is a suggestion for consolidating the 
macros over the files here.
Overall I think it makes sense to keep "Linux wording" as much as 
possible because those files are using Linux philosophy. But I would be 
open to suggestion here. So would you mind giving a list of things you 
consider "basic aspects to 'Xen wording'"?
Cheers,

--
Julien Grall

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