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Sender: Guenter Roeck <groeck7@gmail.com>
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Date:   Tue, 17 Jan 2023 15:05:12 -0800
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Subject: Re: remove arch/sh
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To:     Geert Uytterhoeven <geert@linux-m68k.org>,
        Rob Landley <rob@landley.net>
Cc:     Christoph Hellwig <hch@lst.de>,
        John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>,
        Yoshinori Sato <ysato@users.sourceforge.jp>,
        Rich Felker <dalias@libc.org>, Arnd Bergmann <arnd@arndb.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        linux-kernel@vger.kernel.org, linux-watchdog@vger.kernel.org,
        devicetree@vger.kernel.org, linux-arch@vger.kernel.org,
        dmaengine@vger.kernel.org, dri-devel@lists.freedesktop.org,
        linux-renesas-soc@vger.kernel.org, linux-i2c@vger.kernel.org,
        linux-input@vger.kernel.org, linux-media@vger.kernel.org,
        linux-mmc@vger.kernel.org, linux-mtd@lists.infradead.org,
        netdev@vger.kernel.org, linux-gpio@vger.kernel.org,
        linux-rtc@vger.kernel.org, linux-spi@vger.kernel.org,
        linux-serial@vger.kernel.org, linux-usb@vger.kernel.org,
        linux-fbdev@vger.kernel.org, alsa-devel@alsa-project.org,
        linux-sh@vger.kernel.org
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 <11e2e0a8-eabe-2d8c-d612-9cdd4bcc3648@physik.fu-berlin.de>
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 <9325a949-8d19-435a-50bd-9ebe0a432012@landley.net>
 <CAMuHMdUJm5QvzH8hvqwvn9O6qSbzNOapabjw5nh9DJd0F55Zdg@mail.gmail.com>
From:   Guenter Roeck <linux@roeck-us.net>
In-Reply-To: <CAMuHMdUJm5QvzH8hvqwvn9O6qSbzNOapabjw5nh9DJd0F55Zdg@mail.gmail.com>
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On 1/17/23 12:26, Geert Uytterhoeven wrote:
> Hi Rob,
> 
> On Tue, Jan 17, 2023 at 8:01 PM Rob Landley <rob@landley.net> wrote:
>> On 1/16/23 01:13, Christoph Hellwig wrote:
>>> On Fri, Jan 13, 2023 at 09:09:52AM +0100, John Paul Adrian Glaubitz wrote:
>>>> I'm still maintaining and using this port in Debian.
>>>>
>>>> It's a bit disappointing that people keep hammering on it. It works fine for me.
>>>
>>> What platforms do you (or your users) use it on?
>>
>> 3 j-core boards, two sh4 boards (the sh7760 one I patched the kernel of), and an
>> sh4 emulator.
>>
>> I have multiple j-core systems (sh2 compatible with extensions, nommu, 3
>> different kinds of boards running it here). There's an existing mmu version of
>> j-core that's sh3 flavored but they want to redo it so it hasn't been publicly
>> released yet, I have yet to get that to run Linux because the mmu code would
>> need adapting, but the most recent customer projects were on the existing nommu
>> SOC, as was last year's ASIC work via sky130.
> 
> J4 still vaporware?
> 
>> My physical sh4 boards are a Johnson Controls N40 (sh7760 chipset) and the
>> little blue one is... sh4a I think? (It can run the same userspace, I haven't
>> replaced that board's kernel since I got it, I think it's the type Glaubitz is
>> using? It's mostly in case he had an issue I couldn't reproduce on different
>> hardware, or if I spill something on my N40.)
>>
>> I also have a physical sh2 board on the shelf which I haven't touched in years
>> (used to comparison test during j2 development, and then the j2 boards replaced it).
>>
>> I'm lazy and mostly test each new sh4 build under qemu -M r2d because it's
>> really convenient: neither of my physical boards boot from SD card so replacing
>> the kernel requires reflashing soldered in flash. (They'll net mount userspace
>> but I haven't gotten either bootloader to net-boot a kernel.)
> 
> On my landisk (with boots from CompactFLASH), I boot the original 2.6.22
> kernel, and use kexec to boot-test each and every renesas-drivers
> release.  Note that this requires both the original 2.6.22 kernel
> and matching kexec-tools.  Apparently both upstreamed kernel and
> kexec-tools support for SH are different, and incompatible with each
> other, so you cannot kexec from a contemporary kernel.
> I tried working my way up from 2.6.22, but gave up around 2.6.29.
> Probably I should do this with r2d and qemu instead ;-)
> 
> Both r2d and landisk are SH7751.
> 
> Probably SH7722/'23'24 (e.g. Migo-R and Ecovec boards) are also
> worth keeping.  Most on-SoC blocks have drivers with DT support,
> as they are shared with ARM.  So the hardest part is clock and
> interrupt-controller support.
> Unfortunately I no longer have access to the (remote) Migo-R.
> 

Since there are people around with real hardware .... is sh in big endian mode
(sheb) real ? Its qemu support is quite limited; most PCI devices don't work
due to endianness issues. It would be interesting to know if this works better
with real hardware.

Thanks,
Guenter