linux-kernel - Re: [PATCH v3 6/9] kbuild: consolidate Devicetree dtb build rules

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 13 Sep 2018 17:51:55 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:     Rob Herring <robh@...nel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Michal Marek <michal.lkml@...kovi.net>,
        Vineet Gupta <vgupta@...opsys.com>,
        Russell King <linux@...linux.org.uk>,
        Catalin Marinas <catalin.marinas@....com>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Michal Simek <monstr@...str.eu>,
        Ralf Baechle <ralf@...ux-mips.org>,
        James Hogan <jhogan@...nel.org>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Chris Zankel <chris@...kel.net>,
        Max Filippov <jcmvbkbc@...il.com>,
        linux-kbuild <linux-kbuild@...r.kernel.org>,
        arcml <linux-snps-arc@...ts.infradead.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        "moderated list:H8/300 ARCHITECTURE" 
        <uclinux-h8-devel@...ts.sourceforge.jp>,
        Linux MIPS Mailing List <linux-mips@...ux-mips.org>,
        nios2-dev@...ts.rocketboards.org,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        linux-xtensa@...ux-xtensa.org, Will Deacon <will.deacon@....com>,
        Paul Burton <paul.burton@...s.com>, ley.foon.tan@...el.com
Subject: Re: [PATCH v3 6/9] kbuild: consolidate Devicetree dtb build rules

Hi Yamada-san,

On Wed, Sep 12, 2018 at 3:02 AM Masahiro Yamada
<yamada.masahiro@...ionext.com> wrote:
> 2018-09-12 0:40 GMT+09:00 Rob Herring <robh@...nel.org>:
> > On Mon, Sep 10, 2018 at 10:04 AM Rob Herring <robh@...nel.org> wrote:
> >> There is nothing arch specific about building dtb files other than their
> >> location under /arch/*/boot/dts/. Keeping each arch aligned is a pain.
> >> The dependencies and supported targets are all slightly different.
> >> Also, a cross-compiler for each arch is needed, but really the host
> >> compiler preprocessor is perfectly fine for building dtbs. Move the
> >> build rules to a common location and remove the arch specific ones. This
> >> is done in a single step to avoid warnings about overriding rules.
> >>
> >> The build dependencies had been a mixture of 'scripts' and/or 'prepare'.
> >> These pull in several dependencies some of which need a target compiler
> >> (specifically devicetable-offsets.h) and aren't needed to build dtbs.
> >> All that is really needed is dtc, so adjust the dependencies to only be
> >> dtc.
> >>
> >> This change enables support 'dtbs_install' on some arches which were
> >> missing the target.
> >
> > [...]
> >
> >> @@ -1215,6 +1215,33 @@ kselftest-merge:
> >>                 $(srctree)/tools/testing/selftests/*/config
> >>         +$(Q)$(MAKE) -f $(srctree)/Makefile olddefconfig
> >>
> >> +# ---------------------------------------------------------------------------
> >> +# Devicetree files
> >> +
> >> +ifneq ($(wildcard $(srctree)/arch/$(SRCARCH)/boot/dts/),)
> >> +dtstree := arch/$(SRCARCH)/boot/dts
> >> +endif
> >> +
> >> +ifdef CONFIG_OF_EARLY_FLATTREE
> >
> > This can be true when dtstree is unset. So this line should be this
> > instead to fix the 0-day reported error:
> >
> > ifneq ($(dtstree),)
> >
> >> +
> >> +%.dtb : scripts_dtc
> >> +       $(Q)$(MAKE) $(build)=$(dtstree) $(dtstree)/$@
> >> +
> >> +PHONY += dtbs dtbs_install
> >> +dtbs: scripts_dtc
> >> +       $(Q)$(MAKE) $(build)=$(dtstree)
> >> +
> >> +dtbs_install: dtbs
> >> +       $(Q)$(MAKE) $(dtbinst)=$(dtstree)
> >> +
> >> +all: dtbs
> >> +
> >> +endif
>
>
> Ah, right.
> Even x86 can enable OF and OF_UNITTEST.
>
>
>
> Another solution might be,
> guard it by 'depends on ARCH_SUPPORTS_OF'.
>
>
>
> This is actually what ACPI does.
>
> menuconfig ACPI
>         bool "ACPI (Advanced Configuration and Power Interface) Support"
>         depends on ARCH_SUPPORTS_ACPI
>          ...

ACPI is a real platform feature, as it depends on firmware.

CONFIG_OF can be enabled, and DT overlays can be loaded, on any platform,
even if it has ACPI ;-)

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds