linux-kernel - Re: [PATCH] ARM: do not assemble iwmmxt.S with LLVM toolchain

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Date:   Mon, 13 Apr 2020 12:20:57 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Jian Cai <caij2003@...il.com>, Manoj Gupta <manojgupta@...gle.com>,
        Peter Smith <Peter.Smith@....com>,
        Stefan Agner <stefan@...er.ch>,
        Sami Tolvanen <samitolvanen@...gle.com>,
        Ilie Halip <ilie.halip@...il.com>,
        Jian Cai <jiancai@...gle.com>,
        Russell King <linux@...linux.org.uk>,
        Linus Walleij <linus.walleij@...aro.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        Doug Anderson <armlinux@...isordat.com>,
        Benjamin Gaignard <benjamin.gaignard@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        "Steven Rostedt (VMware)" <rostedt@...dmis.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Tejun Heo <tj@...nel.org>,
        "Joel Fernandes (Google)" <joel@...lfernandes.org>,
        Patrick Bellasi <patrick.bellasi@....com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        David Howells <dhowells@...hat.com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        clang-built-linux <clang-built-linux@...glegroups.com>
Subject: Re: [PATCH] ARM: do not assemble iwmmxt.S with LLVM toolchain

On Fri, Apr 10, 2020 at 2:56 AM Arnd Bergmann <arnd@...db.de> wrote:
>
> On Fri, Apr 10, 2020 at 1:28 AM Jian Cai <caij2003@...il.com> wrote:
> >
> > iwmmxt.S contains XScale instructions LLVM ARM backend does not support.
> > Skip this file if LLVM integrated assemmbler or LLD is used to build ARM
> > kernel.
> >
> > Signed-off-by: Jian Cai <caij2003@...il.com>
>
> It clearly makes sense to limit the Kconfig option to compilers that
> can actually build it.
> A few questions though:
>
> - Given that Armada XP with its PJ4B was still marketed until fairly
> recently[1],
>   wouldn't it make sense to still add support for it? Is it a lot of work?

Sorry, can you help me verify from that link that PJ4B uses XSCALE?  I
didn't see references to either in the link provided.  Also, given the
history of XSCALE as noted by Russell, I'm surprised to see Marvell in
the mix.

>
> - Why does the linker have to understand it, rather than just the assembler?

It doesn't, just the assembler is the problem.

>
> [1] http://web.archive.org/web/20191015165247/https://www.marvell.com/embedded-processors/armada/index.jsp



-- 
Thanks,
~Nick Desaulniers