linux-kernel - Re: [PATCH] cmd_dtc: Enable generation of device tree symbols

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:   Tue, 26 Jan 2021 07:42:48 -0600
From:   Rob Herring <robh@...nel.org>
To:     Uwe Kleine-König <uwe@...ine-koenig.org>
Cc:     Masahiro Yamada <masahiroy@...nel.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        cyril@...amax.com, Arnd Bergmann <arnd@...db.de>,
        Maxime Ripard <mripard@...nel.org>,
        DTML <devicetree@...r.kernel.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Frank Rowand <frowand.list@...il.com>
Subject: Re: [PATCH] cmd_dtc: Enable generation of device tree symbols

On Tue, Jan 26, 2021 at 1:27 AM Uwe Kleine-König <uwe@...ine-koenig.org> wrote:
>
> Hello Masahiro,
>
> On 1/25/21 10:53 PM, Masahiro Yamada wrote:
> > On Mon, Jan 25, 2021 at 8:07 PM Uwe Kleine-König <uwe@...ine-koenig.org> wrote:
> >>
> >> Adding the -@ switch to dtc results in the binary devicetrees containing
> >> a list of symbolic references and their paths. This is necessary to
> >> apply device tree overlays e.g. on Raspberry Pi as described on
> >> https://www.raspberrypi.org/documentation/configuration/device-tree.md.
> >>
> >> Obviously the downside of this change is an increas of the size of the
> >> generated dtbs, for an arm out-of-tree build (multi_v7_defconfig):
> >>
> >>          $ du -s arch/arm/boot/dts*
> >>          101380  arch/arm/boot/dts-pre
> >>          114308  arch/arm/boot/dts-post
> >>
> >> so this is in average an increase of 12.8% in size.
> >>
> >> Signed-off-by: Uwe Kleine-König <uwe@...ine-koenig.org>
> >
> >
> > (CCing DT ML.)
>
> makes sense, thanks.
>
> > https://www.spinics.net/lists/linux-kbuild/msg27904.html
> >
> > See Rob's comment:
> >
> > "We've already rejected doing that. Turning on '-@' can grow the dtb
> > size by a significant amount which could be problematic for some
> > boards."
>
> The patch was created after some conversation on irc which continued
> after I sent the patch. I added the participating parties to Cc:.
>
> The (relevant) followups were:
>
> Geert suggested to always generate the symbols and provide a way to
> strip the symbols for installation if and when they are not needed.
>
> Rob said: "I'm less concerned with the size increases, but rather that
> labels go from purely source syntax to an ABI. I'd rather see some
> decision as to which labels are enabled or not."

I've also said move the arm32 dts files to family subdirectories and
enable '-@' per directory. I've posted a script to do the whole thing,
but I think the preference is one-by-one. This is needed anyways if
we're going to start adding overlays which Viresh is working on.

Rob