Re: [RFC 1/2] devlink: add simple fw crash helpers

Hi,

Sorry ... long delay.

quoted

The reason I'm asking is that it's starting to sound like we really
ought to be implementing devlink, but we've got a bunch of
infrastructure that uses the devcoredump, and it'll take time
(significantly so) to change all that...

In devlink world pure FW core dumps are exposed by devlink regions.
An API allowing reading device memory, registers, etc., but also 
creating dumps of memory regions when things go wrong. It should be
a fairly straightforward migration.

Right. We also have regions (various memory pieces, registers, ...).

One issue might be that for devlink we wouldn't want to expose these as
a single blob, I guess, but for devcoredump we already have a custom
format to glue all the things together. Since it seems unlikely that
anyone else would want to use the *iwlwifi* format to glue things
together, we'd have to do something there.

But perhaps that could be a matter of providing a "glue things into a
devcoredump" function that would have a reasonable default but could be
overridden by the driver for those migration cases.

Devlink health is more targeted, the dump is supposed to contain only
relevant information, selected and formatted by the driver. When device
misbehaves driver reads the relevant registers and FW state and creates
a formatted state dump. I believe each element of the dump must fit
into a netlink message (but there may be multiple elements, see
devlink_fmsg_prepare_skb()).

That wouldn't help for our big memory dumps, but OK.

We should be able to convert dl-regions dumps and dl-health dumps into
devcoredumps, but since health reporters are supposed to be more
targeted there's usually multiple of them per device.

Right.

Conversely devcoredumps can be trivially exposed as dl-region dumps,
but I believe dl-health would require driver changes to format the
information appropriately.

Agree.

Anyway, thanks. I'll put it on my list of things to look at ... not too
hopeful that will be soon, given how long it even took me to get back to
this email :)

johannes