Re: [PATCH] powerpc: Update all configs using savedefconfig

Re: [PATCH] powerpc: Update all configs using savedefconfig

[Geert Uytterhoeven]

Hi Michael,

On Tue, Jan 20, 2015 at 8:05 AM, Michael Ellerman <mpe@ellerman.id.au> wrote:
> It looks like it's ~4 years since we updated some of these, so do a bulk
> update.
>
> Verified that the before and after generated configs are exactly the
> same.

Yep, that's guaranteed by the tool (modulo bugs).

> Which begs the question why update them? The answer is that it can be
> confusing when the stored defconfig drifts too far from the generated
> result.

And it becomes hard to update them, e.g. for enabling or disabling a single
option.

Now the big question is: do they still work?
Plainly ignoring any bugs introduced in the code, there are probably several
"select" statements that have been removed. 4 years ago, they automatically
selected some critical options, while now, they're no longer selected, causing
breakage.

I'm afraid the only safe way is (for all 108 defconfig files):
  - start from the full .config file, as generated from the minimal defconfig
    file in a source tree from 4 years ago,
  - run "make oldconfig" (boring),
  - run "make savedefconfig",
  - update the minimal defconfig.

The boring step can be made a little bit less boring by making a diff between
the .config versions before and after running the first "make oldconfig",
and applying that to the later .config files first, but it's still a tedious
task, especially after 4 years. That's why I do this (for m68k) on every rc
release.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH] powerpc: Update all configs using savedefconfig

[Michael Ellerman]

On Mon, 2015-02-23 at 10:59 +0100, Geert Uytterhoeven wrote:
> Hi Michael,
> 
> On Tue, Jan 20, 2015 at 8:05 AM, Michael Ellerman <mpe@ellerman.id.au> wrote:
> > It looks like it's ~4 years since we updated some of these, so do a bulk
> > update.
> >
> > Verified that the before and after generated configs are exactly the
> > same.
> 
> Yep, that's guaranteed by the tool (modulo bugs).
> 
> > Which begs the question why update them? The answer is that it can be
> > confusing when the stored defconfig drifts too far from the generated
> > result.
> 
> And it becomes hard to update them, e.g. for enabling or disabling a single
> option.
> 
> Now the big question is: do they still work?
> Plainly ignoring any bugs introduced in the code, there are probably several
> "select" statements that have been removed. 4 years ago, they automatically
> selected some critical options, while now, they're no longer selected, causing
> breakage.

Yeah true. So far no one has yelled at me, so perhaps we got lucky :)

cheers