Re: [PATCH v3] panic: keep blinking in spite of long spin timermode

From: Andrew Morton
Date: Thu Jun 17 2010 - 18:20:46 EST


On Fri, 18 Jun 2010 06:36:31 +0900
TAMUKI Shoichi <tamuki@xxxxxxxxxxx> wrote:

> To keep panic_timeout accuracy when running under a hypervisor, the
> current implementation only spins on long time (1 second) calls to
> mdelay. That brings a good effect, but the problem is the keyboard
> LEDs don't blink at all on that situation.
>
> This patch changes to call to panic_blink_enter() between every mdelay
> and keeps blinking in spite of long spin timer mode.
>
> The default time to call to mdelay is 1ms. It will be switched to
> longer if the CONFIG_PANIC_LONGSPIN_TIMER kernel configuration option
> is enabled. This feature is helpful when running under a hypervisor.
>
> Signed-off-by: TAMUKI Shoichi <tamuki@xxxxxxxxxxx>
> ---
> Changes since v2.1:
> - get rid of panicblink= kernel parameter
> - introduce new kernel config option CONFIG_PANIC_LONGSPIN_TIMER
>

I still don't get it :(

Why can't we simply do

for (i = 0; ; i++) {
(*panic_blink)(i & 1);
mdelay(250);
touch_nmi_watchdog();
}

on all kernels, regardless of virtualisation, etc?
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