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

[Michael Ellerman]

Claudio Carvalho <cclaudio at linux.ibm.com> writes:
> On 8/23/19 9:48 AM, Michael Ellerman wrote:
>> 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.

Thanks.

> Currently, the ultravisor memory console DT property is in
> /ibm,opal/ibm,opal-uv-memcons. I think we should move it to
> /ibm,ultravisor/ibm,uv-firmware/ibm,uv-memcons. What do you think?

Yes that looks better.

As an aside, you don't really need to namespace every node and property
under ibm,ultravisor, the top-level ibm,ultravisor is already a
namespace of sorts.

ie. it could just be: /ibm,ultravisor/firmware/memcons

But if it's too late to change those paths it doesn't really matter.

cheers