Re: kern/60918: Keyboard modifier keys are not checked correctly when sent simultaneously

["Phil Hagelberg via gnats" <gnats-admin%NetBSD.org@localhost>]

The following reply was made to PR kern/60918; it has been noted by GNATS.

From: Phil Hagelberg <phil%hagelb.org@localhost>
To: "Michael van Elst via gnats" <gnats-admin%NetBSD.org@localhost>
Cc: kern-bug-people%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost,  gnats-bugs%netbsd.org@localhost
Subject: Re: kern/60918: Keyboard modifier keys are not checked correctly
 when sent simultaneously
Date: Fri, 23 Oct 2026 08:25:12 -0700

 --=-=-=
 Content-Type: text/plain
 Content-Transfer-Encoding: quoted-printable
 
 "Michael van Elst via gnats" <gnats-admin%NetBSD.org@localhost> writes:
 
 >  Another possibility is to generate events for the modifier keycodes
 >  224..231 first, or by simply scanning the keycodes in reverse order.
 
 I've tested this, and scanning in reverse order does fix it; see the
 patch below.
 
 =2DPhil
 
 From=207b573278d25787b4028d37bce780d815a09345b2 Mon Sep 17 00:00:00 2001
 From: Phil Hagelberg <phil%hagelb.org@localhost>
 Subject: [PATCH] Reverse order of keys added in ukbd_decode.
 
 If a single USB report is received that sets both the shift key and A
 at the same time, it should be interpreted as A, but it currently
 results in lower-case a, because the A key is handled first, and then
 the shift key is handled.
 
 Reversing the order is a little cheesy, but it ensures that the shift
 key is handled first.
 =2D--
  sys/dev/usb/ukbd.c | 4 +++-
  1 file changed, 3 insertions(+), 1 deletion(-)
 
 diff --git a/sys/dev/usb/ukbd.c b/sys/dev/usb/ukbd.c
 index 4c81c78f5834..d646abe2b231 100644
 =2D-- a/sys/dev/usb/ukbd.c
 +++ b/sys/dev/usb/ukbd.c
 @@ -821,7 +821,9 @@ ukbd_decode(struct ukbd_softc *sc, struct ukbd_data *ud)
  		ukbd_translate_keycodes(sc, ud, trtab_apple_iso);
 
  	nkeys =3D 0;
 =2D	for (i =3D 0; i < MAXKEYS; i++) {
 +	/* traverse in reverse order so that modifiers are processed first since
 +	 * they can affect the other keys. */
 +	for (i =3D MAXKEYS - 1; i >=3D 0; i--) {
  #ifdef GDIUM_KEYBOARD_HACK
  			if (sc->sc_flags & FLAG_GDIUM_FN && i =3D=3D 0x82) {
  				if (isset(ud->keys, i))
 =2D-
 2.55.0
 
 --=-=-=
 Content-Type: application/pgp-signature; name="signature.asc"
 
 -----BEGIN PGP SIGNATURE-----
 
 iQJEBAEBCgAuFiEEnRPZQmoIFLM3PPXj2KgkNXenhZ8FAmrbfFgQHHBoaWxAaGFn
 ZWxiLm9yZwAKCRDYqCQ1d6eFn8WGEACq5kcHHcPr9VlYsPmpv3/qQIWFx0IpHKn8
 /j2jKEF84UH3rmr42Qjy5a1u7bbxuBEq14H4OBnQmEexAT5NbXfrm8eAEekJbsP0
 Z1fKNLQv1Ljnfk90LtUSGTu+ZLkhGVab2304YsV7YYMc1wgeulEKwcyqZTYoPE9d
 lr66HrbbFIkhVZEuDFK6YyLzg2F+7CSvwwn3cVINaw8fGa4HCWTZZ/X28XPWd8AB
 Wd74cPlxU30lm8PmNYsLb9FIHo9HyTwLKxsHdrIFwyRttbxhgr8aCL8Au43AaD0o
 ia4n5v46hNY+XtM0f7nYrjuMId6wmR6rRUHb4WXwurXxHabl7i8ctYR0hRJpTrg8
 NQ/LCf0dsANzIq6dFbz7lVLaLQxUtQAP6sJKBDoLOwsTnJKv+0y6g19z5GgQEBVA
 Q7LW0CHNPF5H1TKqnqG6Kl13ZqPCGSIPhSsXfPutlBLxcFARQAth3sTPF2S8xpKp
 M1+GLnRU0OMUmghYjZNGLdz05K5qY3BOL05qdoxEmbz2HAR3FBvvTUXk5Ooqb4jc
 Ha09LopjZX2zBVSFKEeJ4Uhf68f+8ZPqXpdpaC1NRifluryY3m8jiuMjchNdz31P
 hC2hqQ+0tCgA5QABGFQczJeSO5GE5t6veBjurUtFCM9fN69g0w8MCjmAoHaY3qjo
 5mFGRlpnEA==
 =ck6u
 -----END PGP SIGNATURE-----
 --=-=-=--