Hi Andrzej,
On Fri, Jun 19, 2020 at 06:28:19PM +0200, Andrzej Pietrasiewicz wrote:
> There exist machines which don't have SysRq key at all, e.g. chromebooks.
>
> This patch allows configuring an alternative key to act as SysRq. Devices
> which declare KEY_SYSRQ in their 'keybit' bitmap continue using KEY_SYSRQ,
> but other devices use the alternative SysRq key instead, by default F10.
> Which key is actually used can be modified with sysrq's module parameter.
I guess you will be removing KEY_SYSRQ form all Chrome OS internal AT
keyboards and external USB keyboard with Chrome OS layouts as well? Via
udev keymap? I suppose this could work... Or have a per device setting
as we allocate a separate handle for each input device attached to the
SysRq handler.
>
> Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@xxxxxxxxxxxxx>
> ---
> drivers/tty/sysrq.c | 28 +++++++++++++++++++++++++---
> 1 file changed, 25 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
> index 0dc3878794fd..e1d271c84746 100644
> --- a/drivers/tty/sysrq.c
> +++ b/drivers/tty/sysrq.c
> @@ -604,6 +604,7 @@ EXPORT_SYMBOL(handle_sysrq);
>
> #ifdef CONFIG_INPUT
> static int sysrq_reset_downtime_ms;
> +static unsigned short alternative_sysrq_key = KEY_F10;
>
> /* Simple translation table for the SysRq keys */
> static const unsigned char sysrq_xlate[KEY_CNT] =
> @@ -621,6 +622,7 @@ struct sysrq_state {
> unsigned long key_down[BITS_TO_LONGS(KEY_CNT)];
> unsigned int alt;
> unsigned int alt_use;
> + unsigned short sysrq_key;
> bool active;
> bool need_reinject;
> bool reinjecting;
> @@ -770,10 +772,10 @@ static void sysrq_reinject_alt_sysrq(struct work_struct *work)
>
> /* Simulate press and release of Alt + SysRq */
> input_inject_event(handle, EV_KEY, alt_code, 1);
> - input_inject_event(handle, EV_KEY, KEY_SYSRQ, 1);
> + input_inject_event(handle, EV_KEY, sysrq->sysrq_key, 1);
> input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
>
> - input_inject_event(handle, EV_KEY, KEY_SYSRQ, 0);
> + input_inject_event(handle, EV_KEY, sysrq->sysrq_key, 0);
> input_inject_event(handle, EV_KEY, alt_code, 0);
> input_inject_event(handle, EV_SYN, SYN_REPORT, 1);
>
> @@ -805,6 +807,7 @@ static bool sysrq_handle_keypress(struct sysrq_state *sysrq,
> }
> break;
>
> +key_sysrq:
> case KEY_SYSRQ:
> if (value == 1 && sysrq->alt != KEY_RESERVED) {
> sysrq->active = true;
> @@ -825,11 +828,15 @@ static bool sysrq_handle_keypress(struct sysrq_state *sysrq,
> * triggering print screen function.
> */
> if (sysrq->active)
> - clear_bit(KEY_SYSRQ, sysrq->handle.dev->key);
> + clear_bit(sysrq->sysrq_key, sysrq->handle.dev->key);
>
> break;
>
> default:
> + /* handle non-default sysrq key */
> + if (code == sysrq->sysrq_key)
> + goto key_sysrq;
> +
> if (sysrq->active && value && value != 2) {
> sysrq->need_reinject = false;
> __handle_sysrq(sysrq_xlate[code], true);
> @@ -924,6 +931,14 @@ static int sysrq_connect(struct input_handler *handler,
> sysrq->handle.private = sysrq;
> timer_setup(&sysrq->keyreset_timer, sysrq_do_reset, 0);
>
> + if (test_bit(KEY_SYSRQ, dev->keybit)) {
> + sysrq->sysrq_key = KEY_SYSRQ;
> + pr_info("%s: using default sysrq key [%x]\n", dev->name, KEY_SYSRQ);
> + } else {
> + sysrq->sysrq_key = alternative_sysrq_key;
> + pr_info("%s: Using alternative sysrq key: [%x]\n", dev->name, sysrq->sysrq_key);
> + }
This is way too noisy IMO.
> +
> error = input_register_handle(&sysrq->handle);
> if (error) {
> pr_err("Failed to register input sysrq handler, error %d\n",
> @@ -1032,6 +1047,13 @@ module_param_array_named(reset_seq, sysrq_reset_seq, sysrq_reset_seq,
>
> module_param_named(sysrq_downtime_ms, sysrq_reset_downtime_ms, int, 0644);
>
> +module_param(alternative_sysrq_key, ushort, 0644);
> +MODULE_PARM_DESC(alternative_sysrq_key,
> + "Alternative SysRq key for input devices that don't have SysRq key. F10 by default.\n"
> + "Example\n"
> + "Using F9 as SysRq:\n"
> + "sysrq.alternative_sysrq_key=0x43\n");
> +
> #else
>
> static inline void sysrq_register_handler(void)
>
> base-commit: 3d77e6a8804abcc0504c904bd6e5cdf3a5cf8162
> --
> 2.17.1
>
--
Dmitry
