From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Gabriel C <nix.or.die@gmail.com>,
Benjamin Gilbert <bgilbert@redhat.com>,
linux-x86_64@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>, X86 ML <x86@kernel.org>,
bero@lindev.ch, Andi Kleen <ak@linux.intel.com>,
Michal Marek <michal.lkml@markovi.net>
Subject: Re: 4.17.x won't boot due to "x86/boot/compressed/64: Handle 5-level paging boot if kernel is above 4G"
Date: Fri, 6 Jul 2018 19:29:28 +0300 [thread overview]
Message-ID: <20180706162928.73jfqtdwdcwtagui@kshutemo-mobl1> (raw)
In-Reply-To: <CAK7LNAS9VuoUakpYEfdo5Bki4eic1QuruvNOfra8oUWUn0embA@mail.gmail.com>
On Fri, Jul 06, 2018 at 11:13:02PM +0900, Masahiro Yamada wrote:
> >> LDFLAGS is for internal-use.
> >> Please do not override it from the command line.
> >
> > Can we generate a build error if a user try to override LDFLAGS, CFLAGS or
> > other critical internal-use-only variables?
>
> Yes, Make can check where variables came from.
I think we should do this.
> >> make LDFLAGS_KERNEL=... LDFLAGS_MODULE=...
> >> will allow you to append linker flags.
> >
> > Okay. It makes me wounder if we should taint kernel in such cases?
> > Custom compiler/linker flags are risky and can lead to weird bugs.
>
> OK.
> So, what problem are we discussing?
Users set custom LDFLAGS/CFLAGS and break kernel. Then report bug that
hard to debug. See
https://bugzilla.kernel.org/show_bug.cgi?id=200385
and start of this thread:
https://lore.kernel.org/lkml/20180701213243.GA20180@trogon.sfo.coreos.systems/
It took me a while to track down the issue. I blamed linker for a while.
> > I've got it wrong. *Any* LDFLAGS option passed to make this way:
> >
> > make LDFLAGS="..."
>
> In your previous mail, I thought you were asking me how to pass
> custom linker flags.
>
> If not, we do not need to think about that case.
> Just say "Do not do that".
At least we need to make user aware about risk of setting custom flags.
--
Kirill A. Shutemov
next prev parent reply other threads:[~2018-07-06 16:29 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAF=P+=5c-baQp-CK1ViG8h=mMRv6d3EgEsN_U4rbBx-Pwv_Krw@mail.gmail.com>
2018-07-01 21:32 ` Benjamin Gilbert
2018-07-02 9:34 ` Kirill A. Shutemov
2018-07-02 19:01 ` Benjamin Gilbert
2018-07-03 8:30 ` Kirill A. Shutemov
2018-07-03 8:59 ` Thomas Gleixner
2018-07-03 11:01 ` Kirill A. Shutemov
2018-07-03 11:24 ` Gabriel C
2018-07-03 12:44 ` Kirill A. Shutemov
2018-07-03 14:02 ` Thomas Gleixner
2018-07-03 14:07 ` Bernhard Rosenkraenzer
2018-07-03 14:19 ` Thomas Gleixner
2018-07-03 14:21 ` Kirill A. Shutemov
2018-07-03 14:27 ` Thomas Gleixner
2018-07-03 18:03 ` Andi Kleen
2018-07-03 20:26 ` Kirill A. Shutemov
2018-07-03 21:00 ` Andi Kleen
2018-07-04 3:10 ` Benjamin Gilbert
2018-07-04 13:21 ` Kirill A. Shutemov
2018-07-04 15:08 ` Kirill A. Shutemov
2018-07-04 20:42 ` Benjamin Gilbert
2018-07-06 6:37 ` Masahiro Yamada
2018-07-06 10:41 ` Kirill A. Shutemov
2018-07-06 14:13 ` Masahiro Yamada
2018-07-06 14:39 ` Gabriel C
2018-07-06 16:33 ` Kirill A. Shutemov
2018-07-06 17:31 ` Gabriel C
2018-07-07 0:55 ` Masahiro Yamada
2018-07-06 16:29 ` Kirill A. Shutemov [this message]
2018-07-06 18:11 ` Andi Kleen
2018-07-06 19:34 ` Benjamin Gilbert
2018-07-07 1:21 ` Masahiro Yamada
2018-07-09 10:10 ` Kirill A. Shutemov
2018-07-09 10:37 ` Masahiro Yamada
2018-07-25 17:26 Dmitry Malkin
2018-07-25 21:21 ` Kirill A. Shutemov
2018-07-26 8:10 ` Dmitry Malkin
2018-07-26 14:50 ` Kirill A. Shutemov
2018-07-26 16:21 ` Dmitry Malkin
2018-07-27 13:46 ` Kirill A. Shutemov
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