[PATCH v2] powerpc/powernv: Add ultravisor message log interface

[Vaidyanathan Srinivasan]

* Claudio Carvalho <cclaudio at linux.ibm.com> [2019-08-24 23:19:19]:

> 
> On 8/23/19 9:48 AM, Michael Ellerman wrote:
> > Hi Claudio,
> 
> Hi Michael,
> 
> >
> > Claudio Carvalho <cclaudio at linux.ibm.com> writes:
> >> Ultravisor (UV) provides an in-memory console which follows the OPAL
> >> in-memory console structure.
> >>
> >> This patch extends the OPAL msglog code to also initialize the UV memory
> >> console and provide a sysfs interface (uv_msglog) for userspace to view
> >> the UV message log.
> >>
> >> CC: Madhavan Srinivasan <maddy at linux.vnet.ibm.com>
> >> CC: Oliver O'Halloran <oohall at gmail.com>
> >> Signed-off-by: Claudio Carvalho <cclaudio at linux.ibm.com>
> >> ---
> >> This patch depends on the "kvmppc: Paravirtualize KVM to support
> >> ultravisor" patchset submitted by Claudio Carvalho.
> >> ---
> >>  arch/powerpc/platforms/powernv/opal-msglog.c | 99 ++++++++++++++------
> >>  1 file changed, 72 insertions(+), 27 deletions(-)
> > I think the code changes look mostly OK here.
> >
> > But I'm not sure about the end result in sysfs.
> >
> > If I'm reading it right this will create:
> >
> >  /sys/firmware/opal/uv_msglog
> >
> > Which I think is a little weird, because the UV is not OPAL.
> >
> > So I guess I wonder if the file should be created elsewhere to avoid any
> > confusion and keep things nicely separated.
> >
> > Possibly /sys/firmware/ultravisor/msglog ?
> 
> 
> Yes, makes sense. I will do that.

+1

Letting the UV have its own /sys/firmware/ultravisor/xxx is a good
idea. We may have a need to export more runtime data from UV for
debug/profile purposes and this sysfs directory will come handy.

--Vaidy