linux-kernel - Re: [PATCH v3] sh: avoid using IRQ0 on SH3/4

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Date:   Sat, 30 Apr 2022 05:30:05 -0500
From:   Rob Landley <rob@...dley.net>
To:     John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>,
        Sergey Shtylyov <s.shtylyov@....ru>,
        Rich Felker <dalias@...c.org>, linux-sh@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH v3] sh: avoid using IRQ0 on SH3/4

On 4/29/22 09:24, John Paul Adrian Glaubitz wrote:
> Hi Sergey!
> 
> On 4/27/22 20:46, Sergey Shtylyov wrote:
>> Using IRQ0 by the platform devices is going to be disallowed soon (see [1])
>> and even now, when IRQ0 is about to be returned by platfrom_get_irq(), you
>> see a big warning.  The code supporting SH3/4 SoCs maps the IRQ #s starting
>> at 0 -- modify that code to start the IRQ #s from 16 instead.
>> 
>> The patch should mostly affect the AP-SH4A-3A/AP-SH4AD-0A boards as they
>> indeed use IRQ0 for the SMSC911x compatible Ethernet chip...
> 
> Maybe try getting it landed through Andrew Morton's tree?

As I told him in IRC, the problem is still that sh4 never gives me a shell
prompt with this patch applied. I just reconfirmed it against current git:

Freeing unused kernel image (initmem) memory: 124K
This architecture does not have kernel memory protection.
Run /init as init process
mountpoint: dev/pts: No such file or directory
8139cp 0000:00:02.0 eth0: link up, 100Mbps, full-duplex, lpa 0x05E1

It makes it partway through the init script, but it hangs with qemu-system-sh4
stuck in a CPU-eating loop before finishing. Without the patch, I get a shell
prompt.

If you don't want to build the userspace from source with mkroot, the last
release's binary tarball is 4 megs and reproduced the problem just fine. First,
confirm it works as-shipped:

$ wget https://landley.net/toybox/downloads/binaries/mkroot/latest/sh4.tgz
...
$ tar xvf sh4.tgz
...
$ cd sh4
$ ./qemu-sh4.sh
...
printk: console [netcon0] enabled
netconsole: network logging started
Freeing unused kernel image (initmem) memory: 116K
This architecture does not have kernel memory protection.
Run /init as init process
8139cp 0000:00:02.0 eth0: link up, 100Mbps, full-duplex, lpa 0x05E1
random: fast init done
Type exit when done.
# exit
reboot: Restarting system

landley@...ftwood:~/sub/sh4$

Once you've confirmed that works with your qemu-system-sh4 install, replace the
kernel using the config in that directory:

$ git clone ~/linux/linux linux
...
$ cd linux
$ patch -p1 -i ~/linux/sh4irq.eml
...
$ CROSS_COMPILE=~/mcm/ccc/sh4-linux-musl-cross/bin/sh4-linux-musl- make \
  ARCH=sh allnoconfig KCONFIG_ALLCONFIG=../miniconfig-sh4
...
$ CROSS_COMPILE=~/mcm/ccc/sh4-linux-musl-cross/bin/sh4-linux-musl- make \
  ARCH=sh -j $(nproc)
...
$ cp arch/sh/boot/zImage ..
$ cd ..
$ ./qemu-*.sh
...

and it hangs without ever saying "random: fast init done" or giving a prompt.

(You could also use the linux-fullconfig file to build your kernel, but you'll
have to say "n" to a bunch of make oldconfig questions.)

> Adrian

Rob