From: Randy Dunlap <rdunlap@infradead.org>
To: Paul Gortmaker <paul.gortmaker@windriver.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Ingo Molnar <mingo@kernel.org>,
Masahiro Yamada <yamada.masahiro@socionext.com>,
Michal Marek <michal.lkml@markovi.net>
Cc: linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [Regression 4.15] Can't kill CONFIG_UNWINDER_ORC with fire or plague.
Date: Thu, 28 Dec 2017 11:29:26 -0800 [thread overview]
Message-ID: <d053e6df-ed00-2a02-eb27-4287b7549276@infradead.org> (raw)
In-Reply-To: <20171226043003.GB10431@windriver.com>
On 12/25/2017 08:30 PM, Paul Gortmaker wrote:
> There is a regression new to 4.15 that happens in a rather common
> workflow which results in the frustrating situation where the user has
> clearly disabled UNWINDER_ORC in their ".config" file, and yet they
> still get the immediate false error saying they need libelf-dev since
> "CONFIG_UNWINDER_ORC=y" is still set, and hence they can not build.
>
> The regression requires UNWINDER_ORC=y (now the default in commit
> fc72ae40e303) followed by the user subsequently disabling it, which is
> common if the user doesn't have libelf-dev and doesn't care about ORC.
>
> This happens because the recently added test in the top level Makefile
> assumes that ,config data will be mapped into include/config/auto.conf
> either by the end user running "make oldconfig" or the Makefile itself
> detecting that "silentoldconfig" should be run. As the simple
> reproducer below shows, this clearly does not happen as expected.
>
> Note that the test for CONFIG_STACK_VALIDATION and libelf-dev in the
> same place in the Makefile is broken in the same way, but since it is a
> warning and not an error, nobody cared about the bogus false positives.
Yeah, that's odd.
> Since there is no way I'm going to debug Makefile stuff on Christmas
> Day, I figured that I should at least report it intstead. The work
> around is to save your .config and run a "make distclean" or manually
> clobber the stale include/config/auto.conf or similar. But a frustrated
> user wouldn't know that w/o the root cause...
>
I have tried to reproduce this multiple times but cannot do so.
It remains with:
> grep UNWINDER .config
# CONFIG_UNWINDER_ORC is not set
CONFIG_UNWINDER_FRAME_POINTER=y
>
> --------------------- reproducer ------------------------
>
> paul@gw:~/git/linux-head$ git describe
> v4.15-rc5
> paul@gw:~/git/linux-head$ make distclean
> paul@gw:~/git/linux-head$ make defconfig
> HOSTCC scripts/basic/fixdep
> HOSTCC scripts/kconfig/conf.o
> SHIPPED scripts/kconfig/zconf.tab.c
> SHIPPED scripts/kconfig/zconf.lex.c
> HOSTCC scripts/kconfig/zconf.tab.o
> HOSTLD scripts/kconfig/conf
> *** Default configuration is based on 'x86_64_defconfig'
> #
> # configuration written to .config
> #
> paul@gw:~/git/linux-head$ make
> scripts/kconfig/conf --silentoldconfig Kconfig
> Makefile:926: *** "Cannot generate ORC metadata for CONFIG_UNWINDER_ORC=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel". Stop.
> paul@gw:~/git/linux-head$ vi .config # disable ORC in favour of FRAME_POINTER
> paul@gw:~/git/linux-head$ make oldconfig
> scripts/kconfig/conf --oldconfig Kconfig
> #
> # configuration written to .config
> #
> paul@gw:~/git/linux-head$ grep UNWINDER .config
> # CONFIG_UNWINDER_ORC is not set
> CONFIG_UNWINDER_FRAME_POINTER=y
> paul@gw:~/git/linux-head$ make
> Makefile:926: *** "Cannot generate ORC metadata for CONFIG_UNWINDER_ORC=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel". Stop.
> paul@gw:~/git/linux-head$ ls -l .config include/config/auto.conf
> -rw-rw-r-- 1 paul paul 115953 Dec 25 22:48 .config
> -rw-rw-r-- 1 paul paul 33069 Dec 25 22:46 include/config/auto.conf
> paul@gw:~/git/linux-head$ grep UNWINDER include/config/auto.conf
> CONFIG_UNWINDER_ORC=y
> paul@gw:~/git/linux-head$
>
> --------------------- reproducer ------------------------
--
~Randy
next prev parent reply other threads:[~2017-12-28 19:29 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 [this message]
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
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