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Date:   Tue, 3 Jul 2018 10:38:53 +0200
From:   Ingo Molnar <mingo@kernel.org>
To:     Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        the arch/x86 maintainers <x86@kernel.org>,
        Ingo Molnar <mingo@redhat.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Kees Cook <keescook@chromium.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Thomas Garnier <thgarnie@google.com>,
        "Serge E. Hallyn" <serge@hallyn.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Russell King <linux@armlinux.org.uk>,
        Paul Mackerras <paulus@samba.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Petr Mladek <pmladek@suse.com>,
        James Morris <jmorris@namei.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Nicolas Pitre <nico@linaro.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Jessica Yu <jeyu@kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
        Will Deacon <will.deacon@arm.com>
Subject: Re: [PATCH v9 0/6] add support for relative references in special
 sections
Message-ID: <20180703083853.GA5369@gmail.com>
References: <20180626182802.19932-1-ard.biesheuvel@linaro.org>
 <20180627151510.GE30631@arm.com>
 <CAKv+Gu-dkVEtRmvZwiAUpxPSHrkTVvzeGhCwczEmxRjcgfd+LQ@mail.gmail.com>
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* Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:

> On 27 June 2018 at 17:15, Will Deacon <will.deacon@arm.com> wrote:
> > Hi Ard,
> >
> > On Tue, Jun 26, 2018 at 08:27:55PM +0200, Ard Biesheuvel wrote:
> >> This adds support for emitting special sections such as initcall arrays,
> >> PCI fixups and tracepoints as relative references rather than absolute
> >> references. This reduces the size by 50% on 64-bit architectures, but
> >> more importantly, it removes the need for carrying relocation metadata
> >> for these sections in relocatable kernels (e.g., for KASLR) that needs
> >> to be fixed up at boot time. On arm64, this reduces the vmlinux footprint
> >> of such a reference by 8x (8 byte absolute reference + 24 byte RELA entry
> >> vs 4 byte relative reference)
> >>
> >> Patch #3 was sent out before as a single patch. This series supersedes
> >> the previous submission. This version makes relative ksymtab entries
> >> dependent on the new Kconfig symbol HAVE_ARCH_PREL32_RELOCATIONS rather
> >> than trying to infer from kbuild test robot replies for which architectures
> >> it should be blacklisted.
> >>
> >> Patch #1 introduces the new Kconfig symbol HAVE_ARCH_PREL32_RELOCATIONS,
> >> and sets it for the main architectures that are expected to benefit the
> >> most from this feature, i.e., 64-bit architectures or ones that use
> >> runtime relocations.
> >>
> >> Patch #2 add support for #define'ing __DISABLE_EXPORTS to get rid of
> >> ksymtab/kcrctab sections in decompressor and EFI stub objects when
> >> rebuilding existing C files to run in a different context.
> >
> > I had a small question on patch 3, but it's really for my understanding.
> > So, for patches 1-3:
> >
> > Reviewed-by: Will Deacon <will.deacon@arm.com>
> >
> 
> Thanks all.
> 
> Thomas, Ingo,
> 
> Except for the below tweak against patch #3 for powerpc, which may
> apparently get confused by an input section called .discard without
> any suffixes, this series is good to go, but requires your ack to
> proceed, so I would like to ask you to share your comments and/or
> objections. Also, any suggestions or recommendations regarding the
> route these patches should take are highly appreciated.

LGTM:

Acked-by: Ingo Molnar <mingo@kernel.org>

Regarding route - I suspect -mm would be good, or any other tree that does a lot 
of cross-arch testing?

Thanks,

	Ingo