Re: [PATCH linux dev-4.10 0/6] Add support PECI and PECI hwmon drivers

[Greg KH]

On Thu, Jan 11, 2018 at 12:28:48AM -0800, Joel Stanley wrote:
> On Wed, Jan 10, 2018 at 11:30 PM, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> > On Wed, Jan 10, 2018 at 01:46:34PM -0800, Jae Hyun Yoo wrote:
> >> Thanks for your pointing it out and I totally agree with you. Actually, we
> >> are preparing 4.13 update for now and an another update will be followed up.
> >> As I answered above, I'll rebase this patch set onto the latest kernel.org
> >> mainline. Sorry for my misunderstanding of upstream process.
> >
> > 4.13?  Why that kernel?  It too is obsolete and insecure and
> > unsupported.
> 
> It contains support for our hardware that I have integrated from work
> in progress patches and upstream commits.
> 
> The OpenBMC project, with myself as the kernel maintainer, have
> intentions to regularly move to upstream releases. This takes time and
> effort. This time and effort is balanced with submitting our drivers
> upstream.

Of course, but please do not have your "users" use a kernel that is
known to have bugs and can not be supported.  That would not be good at
all, don't you think?

> > What keeps you all from just always tracking the latest tree from Linus?
> 
> Linus' tree does not contain all of the drivers required to boot
> systems. Many of them are still under review on lkml, and others still
> require rewrite from the vendor tree.

Merging vendor trees into your tree has got to be a complicated mess.
Why try to keep it all together in one place?

And who is responsible for getting the vendor code upstream?  The
individual drivers?  Individual driver submissions should be quite easy,
what is preventing them from getting merged?

> > What is in your tree that is not upstream that requires you to have a
> > kernel tree at all?
> 
> We have PECI, video compression, crypto, USB CDC, DRM (graphics),
> serial GPIO, LPC mailbox for the ASPEED SoC.

What "USB CDC" do you have that is not upstream?  I'll pick on this one
specifically as I don't think I've seen any patches recently submitted
for that driver at all.  Am I just missing them?

The other ones should also all be easy to get merged, with maybe the
exception of the drm stuff due to the speed that subsystem moves at.
But even there, the community is very helpful in getting stuff upstream,
have you asked for help?

> Another silicon vendor has recently joined the project and that brings
> an entire SoC that is not upstream. We have patches on the ARM that
> are under review for this SoC, with more drivers undergoing cleanup in
> order to submit them to the relevant maintainers.

Why are you merging all SoC trees together into one place?  That seems
like a nightmare to manage, especially with git.

> > And if you do have out-of-tree code, why not use a process that makes it
> > trivial to update the base kernel version so that you can keep up to
> > date very easily?  (hint, just using 'git' is not a good way to do
> > this...)
> 
> We have a process that we've been developing under for the past few
> years. I find git to be a great tool for managing Linux kernel trees.
> 
> What would you recommend for managing kernel trees?

quilt is best for a tree that you can not rebase (i.e. a public git
tree).  Otherwise you end up getting patches all mushed together and
hard to extract in any simple way.

Take a clue from the distros that have been managing kernels for decades
and deal with an updated kernel all the time easily.

Good luck, it sounds like you will need it :)

thanks,

greg k-h