linux-kernel - Re: [PATCH v2] Input: xen-kbdfront

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Message-ID: <CAKf6xpsGy7rjK3Rkosevr3dD+64-WqCEzAecBbHEHpBMeAHh7A@mail.gmail.com>
Date:   Wed, 8 Mar 2023 11:26:20 -0500
From:   Jason Andryuk <jandryuk@...il.com>
To:     Mattijs Korpershoek <mkorpershoek@...libre.com>
Cc:     linux-kernel@...r.kernel.org, xen-devel@...ts.xenproject.org,
        Phillip Susi <phill@...susis.net>, stable@...r.kernel.org,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        linux-input@...r.kernel.org
Subject: Re: [PATCH v2] Input: xen-kbdfront - drop keys to shrink modalias

On Thu, Dec 15, 2022 at 8:54 AM Mattijs Korpershoek
<mkorpershoek@...libre.com> wrote:
>
> On Fri, Dec 09, 2022 at 09:26, Jason Andryuk <jandryuk@...il.com> wrote:
>
> > xen kbdfront registers itself as being able to deliver *any* key since
> > it doesn't know what keys the backend may produce.
> >
> > Unfortunately, the generated modalias gets too large and uevent creation
> > fails with -ENOMEM.
> >
> > This can lead to gdm not using the keyboard since there is no seat
> > associated [1] and the debian installer crashing [2].
> >
> > Trim the ranges of key capabilities by removing some BTN_* ranges.
> > While doing this, some neighboring undefined ranges are removed to trim
> > it further.
> >
> > An upper limit of KEY_KBD_LCD_MENU5 is still too large.  Use an upper
> > limit of KEY_BRIGHTNESS_MENU.
> >
> > This removes:
> > BTN_DPAD_UP(0x220)..BTN_DPAD_RIGHT(0x223)
> > Empty space 0x224..0x229
> >
> > Empty space 0x28a..0x28f
> > KEY_MACRO1(0x290)..KEY_MACRO30(0x2ad)
> > KEY_MACRO_RECORD_START          0x2b0
> > KEY_MACRO_RECORD_STOP           0x2b1
> > KEY_MACRO_PRESET_CYCLE          0x2b2
> > KEY_MACRO_PRESET1(0x2b3)..KEY_MACRO_PRESET3(0xb5)
> > Empty space 0x2b6..0x2b7
> > KEY_KBD_LCD_MENU1(0x2b8)..KEY_KBD_LCD_MENU5(0x2bc)
> > Empty space 0x2bd..0x2bf
> > BTN_TRIGGER_HAPPY(0x2c0)..BTN_TRIGGER_HAPPY40(0x2e7)
> > Empty space 0x2e8..0x2ff
> >
> > The modalias shrinks from 2082 to 1550 bytes.
> >
> > A chunk of keys need to be removed to allow the keyboard to be used.
> > This may break some functionality, but the hope is these macro keys are
> > uncommon and don't affect any users.
> >
> > [1] https://github.com/systemd/systemd/issues/22944
> > [2] https://lore.kernel.org/xen-devel/87o8dw52jc.fsf@vps.thesusis.net/T/
> >
> > Cc: Phillip Susi <phill@...susis.net>
> > Cc: stable@...r.kernel.org
> > Signed-off-by: Jason Andryuk <jandryuk@...il.com>
>
> Reviewed-by: Mattijs Korpershoek <mkorpershoek@...libre.com>

Thank you, Mattjis.

Any other thoughts?  Can this patch be applied?

Thanks,
Jason