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From:   Geert Uytterhoeven <geert@linux-m68k.org>
Date:   Mon, 11 Jan 2021 11:28:20 +0100
Message-ID: <CAMuHMdWEwm76v9op9QKWefFc0XqGsqBQshPxR768cFcv9r8H4Q@mail.gmail.com>
Subject: Re: Old platforms: bring out your dead
To:     Arnd Bergmann <arnd@kernel.org>
Cc:     Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Krzysztof Adamski <krzysztof.adamski@nokia.com>,
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Hi Arnd,

On Mon, Jan 11, 2021 at 10:16 AM Geert Uytterhoeven
<geert@linux-m68k.org> wrote:
> On Mon, Jan 11, 2021 at 9:59 AM Arnd Bergmann <arnd@kernel.org> wrote:
> > On Mon, Jan 11, 2021 at 9:19 AM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > > On Fri, Jan 8, 2021 at 11:55 PM Arnd Bergmann <arnd@kernel.org> wrote:
> > > > * MIPS R3000/TX39xx: 32-bit MIPS-II generation, mostly superseded by
> > > >   64-bit MIPS-III (R4000 and higher) starting in 1991. arch/mips still
> > > >   supports these in DECstation and Toshiba Txx9, but it appears that most
> > > >   of those machines are of the 64-bit kind. Later MIPS32 such as 4Kc and
> > > >   later are rather different and widely used.
> > >
> > > I have a (32-bit) RBTX4927 development board in my board farm, boot-test
> > > every bi-weekly renesas-drivers release on it, and fix kernel issues
> > > when they appear.
> >
> > Right, I was specifically thinking of the MIPS-II/R3000 ones here, I know
> > there are users on multiple actively maintained MIPS-III platforms.
> >
> > Regarding 32-bit vs 64-bit kernels, can you clarify what makes this one
> > a 32-bit board? Is this just your preference for which kernel you install,
> > or are there dependencies on firmware or hardware that require running
> > this machine in 32-bit mode?
>
> TX492x is 32-bit (/proc/cpuinfo says mips1/mips2/mips3), TX493x is 64-bit.
> As Debian dropped support for mips3 and older, I'm stuck at a Jessie nfsroot.

Upon closer look, all TX49xx are 64-bit, but the VxWorks boot loader
refuses to boot 64-bit kernels ("Size is incorrect"), hence I settled
for a 32-bit kernel config a long time ago.
Probably I need to write a 32-bit bootwrapper first. which would allow
me to upgrade the Debian userland beyond jessie using mips64el?

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-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