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

[Juergen Gross <jgross@suse.com>]

On 10/04/17 16:18, Oleksandr Andrushchenko wrote:
> 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@suse.com>
>>>>>> ---
>>>>>>     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?

My plan is to add a way to set the resolution of the graphical
console. This will set framebuffer and pointing device resolution in
Xenstore. In case the pointing device is multi-touch the setting
should be done for that device, too.


Juergen