linux-kernel - Re: [PATCH] kernel/panic: Use SYSTEM

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Date:   Thu, 9 May 2019 10:40:44 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     Prasad Sodagudi <psodagud@...eaurora.org>
Cc:     julien.thierry@....com, will.deacon@....com,
        catalin.marinas@....com, mark.rutland@....com,
        lorenzo.pieralisi@....com, akpm@...ux-foundation.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Sudeep Holla <sudeep.holla@....com>
Subject: Re: [PATCH] kernel/panic: Use SYSTEM_RESET2 command for warm reset

On Wed, May 08, 2019 at 06:47:12PM -0700, Prasad Sodagudi wrote:
> Some platforms may need warm reboot support when kernel crashed
> for post mortem analysis instead of cold reboot. So use config
> CONFIG_WARM_REBOOT_ON_PANIC and SYSTEM_RESET2 psci command
> support for warm reset.
>

Please drop all the references to PSCI and SYSTEM_RESET2 including
in subject. This is more generic and PSCIv1.1 with SYSTEM_RESET2 can
make use of it.

> Signed-off-by: Prasad Sodagudi <psodagud@...eaurora.org>
> ---
>  kernel/panic.c    |  4 ++++
>  lib/Kconfig.debug | 10 ++++++++++
>  2 files changed, 14 insertions(+)
> 
> diff --git a/kernel/panic.c b/kernel/panic.c
> index c1fcaad..6ab6675 100644
> --- a/kernel/panic.c
> +++ b/kernel/panic.c
> @@ -198,6 +198,10 @@ void panic(const char *fmt, ...)
>  
>  	console_verbose();
>  	bust_spinlocks(1);
> +#ifdef CONFIG_WARM_REBOOT_ON_PANIC
> +	/* Configure for warm reboot instead of cold reboot. */
> +	reboot_mode = REBOOT_WARM;
> +#endif
>  	va_start(args, fmt);
>  	len = vscnprintf(buf, sizeof(buf), fmt, args);
>  	va_end(args);
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index d695ec1..2a727d8 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -1000,6 +1000,16 @@ config PANIC_TIMEOUT
>  	  value n > 0 will wait n seconds before rebooting, while a timeout
>  	  value n < 0 will reboot immediately.
>  
> +config WARM_REBOOT_ON_PANIC
> +	bool "Warm reboot instead of cold reboot for panic"
> +	default n
> +	help
> +	  Some vendor platform may need warm reboot instead of cold reboot
> +	  for debugging. Before vendor specific power off driver is
> +	  probed, platform always gets cold reset. By setting Y here and
> +	  support for PSCI V1.1 is present from firmware, platform would
> +	  get warm reset instead of cold reset.
> +

Ditto here, drop PSCI reference. Since it's being pushed as generic
solution, expecting anyone reading this to understand what is this PSCI
makes no sense and may be even confusing.

--
Regards,
Sudeep