[Skiboot] [RFC PATCH 10/10] console: add log scraping OPAL call

[Oliver]

On Wed, Jul 5, 2017 at 4:06 PM, Stewart Smith
<stewart at linux.vnet.ibm.com> wrote:
> Oliver O'Halloran <oohall at gmail.com> writes:
>> Adds an OPAL call that parses the OPAL log, finds important messages
>> (log_level below PR_WARN) and copies them up to the OS. This is intended
>> to make firmware error messages more visible to system administrators
>> since it allows the OS the report them in the usual places rather than
>> a OPAL specific log file (e.g. /sys/firmware/opal/msglog under linux).
>>
>> Signed-off-by: Oliver O'Halloran <oohall at gmail.com>
>
>
> So, I've had a renewed bit of thinking on what we should do here, and
> something we could do without too much effort to make a decent
> (and progressive) improvement(s) to getting messages out to users.
>
> I'm thinking that to start with, we may want 2-3 additional bits of info
> being passed to linux:
> 1) is this a message from current boot or previous
>    The logic being that we may be able to go "and here's why you died"
>    on subsequent boot?
>    (I'm not sure on this...)

Maybe, systemd already handles keeping track of error messages across
boots (and kexecs) so I'm not sure this is the best place in the stack
to handle that.

> 2) arbitrary other bit of info (extendable). i.e. we could point to the
>    phandle of the thing that died, the error log id (or some
>    replacement), but the idea being we've set up the call from day 1 to
>    support that.

Getting an error log ID if the error generated one might be useful,
but I don't see what we can do with something like a phandle. Even if
we could localise an error to a phandle we have no idea how that error
should be handled and realistically the driver that did the OPAL call
that caused the error should have handled it.

> 3) Current versus earlier in boot?

I don't think we need to handle this explicitly. At the time
opal_init() is called the kernel will fetch any errors that occured
previously and run time errors are fetched as they occur.