From: Masahiro Yamada <yamada.masahiro@socionext.com>
To: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
Randy Dunlap <rdunlap@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Michal Marek <michal.lkml@markovi.net>,
Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [Regression 4.15] Can't kill CONFIG_UNWINDER_ORC with fire or plague.
Date: Tue, 18 Dec 2018 13:56:56 +0900 [thread overview]
Message-ID: <CAK7LNARfr6dKw=SM1_NyqRPAZ08-HvouzJFJmSox-h9m2RFecA@mail.gmail.com> (raw)
In-Reply-To: <20181216214202.GQ11670@windriver.com>
On Mon, Dec 17, 2018 at 6:45 AM Paul Gortmaker
<paul.gortmaker@windriver.com> wrote:
>
> [Re: [Regression 4.15] Can't kill CONFIG_UNWINDER_ORC with fire or plague.] On 29/12/2017 (Fri 13:18) Paul Gortmaker wrote:
>
> > [Re: [Regression 4.15] Can't kill CONFIG_UNWINDER_ORC with fire or plague.] On 29/12/2017 (Fri 10:47) Josh Poimboeuf wrote:
> >
> > > This seems to be related to a kconfig quirk where only silentoldconfig
> > > updates the include/config/auto.conf file. The other config targets
> > > (oldconfig, defconfig, etc) don't touch it. It seems intentional, but I
> > > have no idea why.
> > >
> > > That causes the Makefile to get stale data for 'CONFIG_*' variables when
> > > it includes auto.conf. So I don't think this is specific to the ORC
> > > check. It seems like it could also cause bugs elsewhere.
> >
> > OK, good - you agree with my initial diagnosis of stale auto.conf then.
> > Not sure what Randy was testing when he said he couldn't reproduce it.
> >
> > > The below (ugly) patch fixes it, though I'm not sure this is the best
> > > way to do it. We probably need Masahiro or Michal to chime in here.
> >
> > Yep, that is why I intentionally put the kbuild folks on the To/Cc of
> > the original report (and ran away screaming at the prospect of debugging
> > Makefiles on xmas day). But with holidays and all, it might not be
> > until early January before they have a chance to reply.
>
> It is nearly a year later and we still have this false positive.
>
> paul@sm:~/git/linux-head$ make -j12 > /dev/null
> Makefile:966: *** "Cannot generate ORC metadata for CONFIG_UNWINDER_ORC=y,
> please install libelf-dev, libelf-devel or elfutils-libelf-devel". Stop.
> paul@sm:~/git/linux-head$ grep UNWINDER_ORC .config
> # CONFIG_UNWINDER_ORC is not set
>
> We do know a bit more now -- the auto.conf issue has been independently
> confirmed and "fixed" for other subsystems/issues since, like RETPOLINE:
>
> ---------------------
> commit 25896d073d8a0403b07e6dec56f58e6c33678207
> Author: Masahiro Yamada <yamada.masahiro@socionext.com>
> Date: Wed Dec 5 15:27:19 2018 +0900
>
> x86/build: Fix compiler support check for CONFIG_RETPOLINE
>
> It is troublesome to add a diagnostic like this to the Makefile
> parse stage because the top-level Makefile could be parsed with
> a stale include/config/auto.conf.
>
> Once you are hit by the error about non-retpoline compiler, the
> compilation still breaks even after disabling CONFIG_RETPOLINE.
> ---------------------
>
> I'm not sure if we want to treat this on a per config option each time
> again and again, or undertake a more global kbuild approach, but it does
> warrant a mention and a re-examination before we "solve" this again.
I did not notice this thread
(perhaps, it fell into my crack during the holidays)
but I actually tried to fix this twice in a sophisticated way
in the past.
The first attempt (https://patchwork.kernel.org/patch/10516049/)
was rejected by Josh Poimboeuf.
The second one (https://patchwork.kernel.org/patch/10643245/)
turned out not working as expected.
Now, I am preparing for the third attempt,
but it will take time for review.
What I can do now is the similar fix-up as commit 25896d073d8.
I will post a cheesy fix-up patch.
--
Best Regards
Masahiro Yamada
prev parent reply other threads:[~2018-12-18 4:57 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-26 4:30 [Regression 4.15] Can't kill CONFIG_UNWINDER_ORC with fire or plague Paul Gortmaker
2017-12-28 19:29 ` Randy Dunlap
2017-12-29 2:13 ` Paul Gortmaker
2017-12-29 16:47 ` Josh Poimboeuf
2017-12-29 18:18 ` Paul Gortmaker
2017-12-29 18:40 ` vcaputo
2018-12-16 21:42 ` Paul Gortmaker
2018-12-18 4:56 ` Masahiro Yamada [this message]
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