linux-kernel - Re: [PATCH] Input: xen-kbdfront - allow better run-time configuration

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Date:   Thu, 19 Apr 2018 16:01:21 +0300
From:   Oleksandr Andrushchenko <andr2000@...il.com>
To:     Juergen Gross <jgross@...e.com>, xen-devel@...ts.xenproject.org,
        linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
        dmitry.torokhov@...il.com, lyan@...e.com,
        boris.ostrovsky@...cle.com
Cc:     andrii_chepurnyi@...m.com,
        Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
Subject: Re: [PATCH] Input: xen-kbdfront - allow better run-time configuration

On 04/19/2018 03:52 PM, Juergen Gross wrote:
> On 19/04/18 13:44, Oleksandr Andrushchenko wrote:
>> On 04/19/2018 02:25 PM, Juergen Gross wrote:
>>> On 18/04/18 17:04, Oleksandr Andrushchenko wrote:
>>>> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
>>>>
>>>> It is now only possible to control if multi-touch virtual device
>>>> is created or not (via the corresponding XenStore entries),
>>>> but keyboard and pointer devices are always created.
>>> Why don't you want to go that route for keyboard and mouse, too?
>>> Or does this really make no sense?
>> Well, I would prefer not to touch anything outside Linux and
>> this driver. And these settings seem to be implementation specific.
>> So, this is why introduce Linux module parameters and don't extend
>> the kbdif protocol.
>>>> In some cases this is not desirable. For example, if virtual
>>>> keyboard device is exposed to Android then the latter won't
>>>> automatically show on-screen keyboard as it expects that a
>>>> physical keyboard device can be used for typing.
>>>>
>>>> Make it possible to configure which virtual devices are created
>>>> with module parameters:
>>>>     - no_ptr_dev=1 if no pointer device needs to be created
>>>>     - no_kbd_dev=1 if no keyboard device needs to be created
>>>> Keep old behavior by default.
>>>>
>>>> Signed-off-by: Oleksandr Andrushchenko
>>>> <oleksandr_andrushchenko@...m.com>
>>>> Suggested-by: Andrii Chepurnyi <andrii_chepurnyi@...m.com>
>>>> Tested-by: Andrii Chepurnyi <andrii_chepurnyi@...m.com>
>>>> ---
>>>>    drivers/input/misc/xen-kbdfront.c | 159 +++++++++++++++++-------------
>>>>    1 file changed, 92 insertions(+), 67 deletions(-)
>>>>
>>>> diff --git a/drivers/input/misc/xen-kbdfront.c
>>>> b/drivers/input/misc/xen-kbdfront.c
>>>> index d91f3b1c5375..a3306aad40b0 100644
>>>> --- a/drivers/input/misc/xen-kbdfront.c
>>>> +++ b/drivers/input/misc/xen-kbdfront.c
>>>> @@ -51,6 +51,16 @@ module_param_array(ptr_size, int, NULL, 0444);
>>>>    MODULE_PARM_DESC(ptr_size,
>>>>        "Pointing device width, height in pixels (default 800,600)");
>>>>    +static unsigned int no_ptr_dev;
>>>> +module_param(no_ptr_dev, uint, 0);
>>> Use type invbool instead?
>> Hm, better bool then? invbool will require parameter name change to
>> something like "with_ptr_dev" which might confuse, e.g.
>> default was to go with pointer device, now we have with_ptr_dev
>> module parameter: do I now need to set it to preserve the old behavior?
>> The answer is no (because of invbool), but you have to dig for it.
>>
>> Will bool work for you?
> As long as the default won't change from today: yes.
Ok, so I'll send v2 with the following changes:

diff --git a/drivers/input/misc/xen-kbdfront.c 
b/drivers/input/misc/xen-kbdfront.c
index a3306aad40b0..d8cca212f737 100644
--- a/drivers/input/misc/xen-kbdfront.c
+++ b/drivers/input/misc/xen-kbdfront.c
@@ -51,13 +51,13 @@ module_param_array(ptr_size, int, NULL, 0444);
  MODULE_PARM_DESC(ptr_size,
         "Pointing device width, height in pixels (default 800,600)");

-static unsigned int no_ptr_dev;
-module_param(no_ptr_dev, uint, 0);
+static bool no_ptr_dev;
+module_param(no_ptr_dev, bool, 0);
  MODULE_PARM_DESC(no_ptr_dev,
         "If set then no virtual pointing device exposed to the guest");

-static unsigned int no_kbd_dev;
-module_param(no_kbd_dev, uint, 0);
+static bool no_kbd_dev;
+module_param(no_kbd_dev, bool, 0);
  MODULE_PARM_DESC(no_kbd_dev,
         "If set then no virtual keyboard device exposed to the guest");


>
> Juergen