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

[Andrew Donnellan]

On 01/09/18 18:17, Vaibhav Jain wrote:
> 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.
> 
> Signed-off-by: Vaibhav Jain <vaibhav at linux.ibm.com>

Oh good, someone else has finally picked this up and sent a kernel 
patch, I did the skiboot half and then neglected to make it useful (I 
sent an RFC at https://patchwork.ozlabs.org/patch/697604/ but never 
followed up on it... this approach seems more usable, I think).

When you say "the reboot command" - is this behaviour of passing the 
argument common to all the important init systems/reboot utils?  What's 
the correct systemd way to do it?

>   	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);

You might want to check for OPAL_UNSUPPORTED here just in case we're 
running on ancient firmware.

> +		else
> +			rc = opal_cec_reboot();
> +
>   		if (rc == OPAL_BUSY_EVENT)
>   			opal_poll_events(NULL);
>   		else
> 

-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan at au1.ibm.com  IBM Australia Limited