[PATCH RFC] powerpc/powernv: sysfs entry to force full IPL reboot

[Michael Ellerman]

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

> skiboot now supports "fast reboot", a reboot procedure where skiboot
> reinitialises hardware and loads a new kernel without re-IPLing the
> machine. At present, fast reboot support is still experimental and is not
> enabled by default, however it is intended that it will be enabled by
> default in a near-future release.
>
> There may be some circumstances where the user wants to force a full IPL
> reboot rather than using fast reboot. Add support for the
> OPAL_REBOOT_FULL_IPL reboot type, enabled by writing 1 to
> /sys/firmware/opal/force_full_ipl_reboot. On versions of skiboot that
> implement the OPAL_REBOOT_FULL_IPL reboot type, this will force an IPL. On
> versions that do not, print an error message on reboot and proceed with a
> regular reboot (which could be a full IPL or a fast reboot).

Hi Andrew,

Can I suggest:
 - Fix OPAL
 - Fix OPAL
 - Fix OPAL

...

Oh OK, it's firmware :D

There's existing logic in kernel/reboot.c to handle a reboot= command
line parameter, which can set the reboot_mode, so my preference would be
that we use that.

Currently we completely ignore the reboot_mode, so there's no backward
compatibility issue.

It looks like the default is REBOOT_COLD, whatever that means. So I
think we could define that on powernv REBOOT_HARD means "do a full IPL".

Or we could use "force", which already exists, though I can't quite see
what that actually means on x86.

cheers