Re: [Xen-devel] [PATCH 1/2] xen, input: add xen-kbdfront module parameter for setting resolution

[Oleksandr Andrushchenko <andr2000@xxxxxxxxx>]

On 04/10/2017 05:11 PM, Juergen Gross wrote:
> On 10/04/17 16:00, Oleksandr Andrushchenko wrote:
> > On 04/10/2017 04:50 PM, Juergen Gross wrote:
> > > On 10/04/17 15:44, Oleksandr Andrushchenko wrote:
> > > > Hi, Juergen!
> > > >
> > > > On 03/21/2017 07:19 PM, Juergen Gross wrote:
> > > > > Add a parameter for setting the resolution of xen-kbdfront in order to
> > > > > be able to cope with a (virtual) frame buffer of arbitrary resolution.
> > > > >
> > > > > Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> > > > > ---
> > > > >     drivers/input/misc/xen-kbdfront.c | 10 ++++++++--
> > > > >     1 file changed, 8 insertions(+), 2 deletions(-)
> > > > >
> > > > > diff --git a/drivers/input/misc/xen-kbdfront.c
> > > > > b/drivers/input/misc/xen-kbdfront.c
> > > > > index 3900875..2df5678 100644
> > > > > --- a/drivers/input/misc/xen-kbdfront.c
> > > > > +++ b/drivers/input/misc/xen-kbdfront.c
> > > > > @@ -41,6 +41,12 @@ struct xenkbd_info {
> > > > >         char phys[32];
> > > > >     };
> > > > >     +enum { KPARAM_WIDTH, KPARAM_HEIGHT, KPARAM_CNT };
> > > > > +static int size[KPARAM_CNT] = { XENFB_WIDTH, XENFB_HEIGHT };
> > > > > +module_param_array(size, int, NULL, 0444);
> > > > is this by intention that you use 0444 here?
> > > > It means read-only, thus one cannot change these,
> > > > so what is the point of the module parameters then?
> > > You can see the settings in sysfs.
> > this is good so we can see actual width/height
> > used by the pv driver
> > > The values are settable via boot parameter.
> > but then, if one has other values set in XenStore,
> > these will/may be overridden, making it inconsistent,
> > e.g. values loaded at start as module parameters
> > (*size* array) is not going to be updated on
> > XenbusStateInitWait/XenbusStateConnected. So, we'll
> > end up with wrong parameters shown via sysfs
> > one more question is why do we need module parameters
> > if the same can be read from XenStore?
> Because up to now nobody is setting the Xenstore values. This is
> something I'm planning to do for Xen 4.10.
ah, good to know. btw, if you are about to add
width/height for the pointer device will you also add
the same for multi-touch?
>   Up to then we need a
> workaround.
>
> But you are right: The module parameters should be updated with
> the values read from Xenstore.
>
>
> Juergen

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