[Xen-devel] Re: [PATCH] xen: change XEN_PLATFORM_PCI to bool default y

[Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>]

On Wed, 2011-09-21 at 19:51 +0100, Konrad Rzeszutek Wilk wrote:
> On Wed, Sep 21, 2011 at 01:37:50PM +0100, stefano.stabellini@xxxxxxxxxxxxx 
> wrote:
> > From: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> > 
> > The xen-platform-pci module is small and for PV on HVM guests is a
> 
> How small?

IIRC it is single digit numbers of kb.

>  Does it get removed from memory if it never gets loaded?
> 
> > requirement for xenbus.
> 
> Ok, should it then have a depency on XenBus as well?

xenbus can't be a module (which is why allowing platform-pci to be is
causing problems).

> Linus does not like the 'default y' very much. He actually dislikes
> it quite much as I found when he tore Dan's behind about cleancache.

In particular case the option is gated on a dependency on another Xen
option (PVHVM) which doesn't default on. But if you do select PVHVM you
certainly want this option, so I think that's ok (why else would
'default y' even exist?)

> .. so I think making it 'default n' is a better option or perhaps
> making it depend on some other functionality? Or perhaps just remove
> the tristate/bool altogether so it gets activated if XEN_PVHVM
> is set?
> 
> Or remove the XEN_PLATFORM_PCI config option completly and make the
> config files that build this driver be CONFIG_XENPVHM dependent?

That would work too. Even better would be to make it an invisible
Kconfig symbol which PVHVM just selects.

Ian.

> 
> > 
> > Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> > ---
> >  drivers/xen/Kconfig |    4 ++--
> >  1 files changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
> > index 5f7ff8e..a64b8e8 100644
> > --- a/drivers/xen/Kconfig
> > +++ b/drivers/xen/Kconfig
> > @@ -138,9 +138,9 @@ config XEN_GRANT_DEV_ALLOC
> >       or as part of an inter-domain shared memory channel.
> >  
> >  config XEN_PLATFORM_PCI
> > -   tristate "xen platform pci device driver"
> > +   bool "xen platform pci device driver"
> >     depends on XEN_PVHVM && PCI
> > -   default m
> > +   default y
> >     help
> >       Driver for the Xen PCI Platform device: it is responsible for
> >       initializing xenbus and grant_table when running in a Xen HVM
> > -- 
> > 1.7.2.3



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