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

[Vaibhav Jain]

Thanks for looking into this Andrew,

Andrew Donnellan <andrew.donnellan at au1.ibm.com> writes:

> 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).
Thanks for pointing that out. I wasnt aware of this patch.


> 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?
Mostly Yes,

On systemd the reboot command is just a symlink to systemctl binary that
checks argv[0] and maintains the a backward compatible behaviour. The
more systemd specific command 'systemctl reboot full' will also do the
same thing. So this patch should work on systemd.

Looking at 'upstart' I see support for adding an arg to the reboot
command since revision
https://bazaar.launchpad.net/~upstart-devel/upstart/trunk/revision/1432.3.1
. So upstart should also be supported.

I dont see support for sending an arg in 'SysVinit' halt command
yet. However this patch wont break the halt command. Just that SysVinit
systems will continue to use fast-reboot like today. Though
theorectially with this patch a SysVinit user can write a tool to issue
reboot syscall with cmd == LINUX_REBOOT_CMD_RESTART2 and arg == "full".

>>   	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.
Good idea, will fix this in v2.

-- 
Vaibhav Jain <vaibhav at linux.vnet.ibm.com>
Linux Technology Center, IBM India Pvt. Ltd.