Subject: Re: [PATCH] powerpc/powernv: Make possible for user to force a full ipl cec reboot

From: Stewart Smith <[email-masked]>
Date: Mon, 10 Sep 2018 14:37:12 +1000

Vaibhav Jain <[email-masked]> writes:
> Ever since fast reboot is enabled by default in opal,
> opal_cec_reboot() will use fast-reset instead of full IPL to perform
> system reboot. This leaves the user with no direct way to force a full
> IPL reboot except changing an nvram setting that persistently disables
> fast-reset for all subsequent reboots.
>
> This patch provides a more direct way for the user to force a one-shot
> full IPL reboot by passing the command line argument 'full' to the
> reboot command. So the user will be able to tweak the reboot behavior
> via:
>
>   $ sudo reboot full	# Force a full ipl reboot skipping fast-reset
>
>   or
>   $ sudo reboot  	# default reboot path (usually fast-reset)
>
> The reboot command passes the un-parsed command argument to the kernel
> via the 'Reboot' syscall which is then passed on to the arch function
> pnv_restart(). The patch updates pnv_restart() to handle this cmd-arg
> and issues opal_cec_reboot2 with OPAL_REBOOT_FULL_IPL to force a full
> IPL reset.

We're about to introduce an MPIPL reboot type (to take a firmware
assisted kdump style thing), and we maybe should have a reboot type to
force attempting a fast-reboot, and this makes me think if we should add
those in now?

>
> Signed-off-by: Vaibhav Jain <[email-masked]>
> ---
>  arch/powerpc/include/asm/opal-api.h    | 1 +
>  arch/powerpc/platforms/powernv/setup.c | 8 +++++++-
>  2 files changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/include/asm/opal-api.h b/arch/powerpc/include/asm/opal-api.h
> index 8365353330b4..870fb7b239ea 100644
> --- a/arch/powerpc/include/asm/opal-api.h
> +++ b/arch/powerpc/include/asm/opal-api.h
> @@ -1050,6 +1050,7 @@ enum OpalSysCooling {
>  enum {
>  	OPAL_REBOOT_NORMAL		= 0,
>  	OPAL_REBOOT_PLATFORM_ERROR	= 1,
> +	OPAL_REBOOT_FULL_IPL		= 2,
>  };
>  
>  /* Argument to OPAL_PCI_TCE_KILL */
> diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c
> index adddde023622..33d2faeacff8 100644
> --- a/arch/powerpc/platforms/powernv/setup.c
> +++ b/arch/powerpc/platforms/powernv/setup.c
> @@ -224,7 +224,13 @@ static void  __noreturn pnv_restart(char *cmd)
>  	pnv_prepare_going_down();
>  
>  	while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
> -		rc = opal_cec_reboot();
> +
> +		/* See if we need to do a full IPL reboot */
> +		if (cmd && strcmp(cmd, "full") == 0)
> +			rc = opal_cec_reboot2(OPAL_REBOOT_FULL_IPL, NULL);
> +		else
> +			rc = opal_cec_reboot();
> +

If the reboot type isn't supported, what should be the behvaiour? Reboot
the default way or don't reboot at all?

-- 
Stewart Smith
OPAL Architect, IBM.