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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Mon, 4 Apr 2022 21:35:47 +0200
Message-ID: <CAK8P3a3iFb+ZacZ40d8PC_xcJpLVFXT0Qc-oYEZNkFqXdsfNZw@mail.gmail.com>
Subject: Re: [RFC PULL] remove arch/h8300
To:     Max Filippov <jcmvbkbc@gmail.com>
Cc:     Arnd Bergmann <arnd@arndb.de>,
        Christoph Hellwig <hch@infradead.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Yoshinori Sato <ysato@users.sourceforge.jp>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-arch <linux-arch@vger.kernel.org>,
        "moderated list:H8/300 ARCHITECTURE" 
        <uclinux-h8-devel@lists.sourceforge.jp>,
        "open list:TENSILICA XTENSA PORT (xtensa)" 
        <linux-xtensa@linux-xtensa.org>,
        Linux-sh list <linux-sh@vger.kernel.org>,
        linux-m68k <linux-m68k@lists.linux-m68k.org>,
        Greg Ungerer <gerg@linux-m68k.org>,
        Damien Le Moal <damien.lemoal@wdc.com>,
        linux-riscv <linux-riscv@lists.infradead.org>
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On Mon, Apr 4, 2022 at 9:14 PM Max Filippov <jcmvbkbc@gmail.com> wrote:
> On Mon, Apr 4, 2022 at 12:01 PM Arnd Bergmann <arnd@arndb.de> wrote:
> > On Mon, Apr 4, 2022 at 7:57 PM Max Filippov <jcmvbkbc@gmail.com> wrote:
> > > Please let me know if you observe any specific build/runtime issues.
> > xtensa-linux-gcc-11.1.0 -DKCONFIG_SEED=
> ...
> > /git/arm-soc/arch/xtensa/kernel/head.S: Assembler messages:
> > /git/arm-soc/arch/xtensa/kernel/head.S:87: Error: invalid register
> > 'atomctl' for 'wsr' instruction
>
> Sure, one cannot use an arbitrary xtensa compiler for the kernel
> build, the compiler configuration must match the core variant selected
> in the linux configuration. Specifically, for the nommu_kc705_defconfig
> the following compiler can be used:
>
> https://github.com/foss-xtensa/toolchain/releases/download/2020.07/x86_64-2020.07-xtensa-de212-elf.tar.gz
>
> If you build the toolchain yourself using crosstool-ng or buildroot they
> accept the 'configuration overlay' parameter that does the compiler
> customization.
>
> Perhaps the documentation for this part is what needs to be improved.

It sounds like a bug in the kernel Makefile. On all other architectures,
you can generally just pick any (recent) compiler and build any kernel,
as the compiler arguments set the exact target machine type based
on the kernel config. You can't normally rely on the compiler defaults
for kernel builds.

         Arnd