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Date:   Thu, 26 Jul 2018 08:00:54 +0200
From:   Martin Schwidefsky <schwidefsky@de.ibm.com>
To:     Kees Cook <keescook@chromium.org>
Cc:     Christian Borntraeger <borntraeger@de.ibm.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Guenter Roeck <linux@roeck-us.net>,
        David Miller <davem@davemloft.net>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Linux 4.18-rc6
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On Wed, 25 Jul 2018 12:40:26 -0700
Kees Cook <keescook@chromium.org> wrote:

> On Tue, Jul 24, 2018 at 12:24 AM, Martin Schwidefsky
> <schwidefsky@de.ibm.com> wrote:
> > On Tue, 24 Jul 2018 09:15:58 +0200
> > Christian Borntraeger <borntraeger@de.ibm.com> wrote:
> >  
> >> On 07/24/2018 08:18 AM, Martin Schwidefsky wrote:  
> >> > On Mon, 23 Jul 2018 16:17:22 -0700
> >> > Linus Torvalds <torvalds@linux-foundation.org> wrote:
> >> >  
> >> >> On Mon, Jul 23, 2018 at 2:23 PM Guenter Roeck <linux@roeck-us.net> wrote:  
> >> >>>  
> >> >>>>
> >> >>>> Martin - can we just remove the
> >> >>>>
> >> >>>>          select HAVE_GCC_PLUGINS
> >> >>>>
> >> >>>> from the s390 Kconfig file (or perhaps add "if BROKEN" or something to
> >> >>>> disable it).
> >> >>>>
> >> >>>> Because if it's not getting fixed, it shouldn't be exposed.
> >> >>>>  
> >> >>> The problem only affects 4.18 - the code has been rearranged in -next.
> >> >>> Only, in my builders, I can't disable a flag for individual releases,
> >> >>> so I just disabled it completely for s390.  
> >> >>
> >> >> Well, I'm not going to release a 4.18 with a known problem, so in 4.18
> >> >> this *will* be disabled if it's not fixed.
> >> >>
> >> >> The fact that it might be fixed in linux-next is entirely immaterial
> >> >> to the release of 4.18.  
> >> >
> >> > Ok, if gcc with the plugins and an allmodconfig is considered to be
> >> > important enough to warrant a fix, it can be pulled from here:
> >> >
> >> > git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux.git for-linus
> >> >
> >> > Martin Schwidefsky (1):
> >> >       s390: disable gcc plugins
> >> >
> >> > Once that is in I will create another patch to undo this one and place
> >> > it after the early boot rework.  
> >>
> >> On the list a different fix was proposed about 2 weeks ago,  
> 
> https://lkml.kernel.org/r/CAGXu5jKyESyPD1MyM7BrVFPKDY9+HqRCpXcKG5ikCZwdGZLaSw@mail.gmail.com
> 
> >>
> >> something like
> >>
> >> CFLAGS_als.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
> >>
> >> and I prefer that. Because your patch disables all gcc plugins.  
> >
> > This change would cause trouble with patch dependencies as als.c is moved
> > to a different directory. I would prefer to disable all gcc plugins for
> > 4.18.  
> 
> I don't understand why not just add it to the Makefile. For -next and
> 4.19, just drop the line again once you merge with 4.18? A CFLAGS_*.o
> entry for a file that doesn't exist should be harmless...
> 
> Of course, if no one is actually using the gcc plugins on s390, then
> okay, disabling them isn't a problem. :) But since it's been working
> on s390 since 4.15, it seems weird to turn all of them off just for
> 4.18 when a trivial fix is available.

The gcc plugins have not in wide-spread use, it is no problem to just
disable them all. The advantage doing the fixing with the Kconfig file
is that I avoid a merge conflict with the current features branch.
And I do not want to rebase that branch this late in the -rcs just
because of this problem.

-- 
blue skies,
   Martin.

"Reality continues to ruin my life." - Calvin.