Re: Running m68k on qemu with external initramfs?

From: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
To: Rob Landley <rob@landley.net>
Cc: Finn Thain <fthain@telegraphics.com.au>,
	linux-m68k@vger.kernel.org, Laurent Vivier <laurent@vivier.eu>
Subject: Re: Running m68k on qemu with external initramfs?
Date: Sun, 12 Apr 2020 10:27:28 +0200	[thread overview]
Message-ID: <08DCD73D-7BC1-4F38-87DE-ED4DBD5978DA@physik.fu-berlin.de> (raw)
In-Reply-To: <0e69cfc4-3bcd-25c3-0d32-665ef50f815c@landley.net>

Hi!

> On Apr 12, 2020, at 5:31 AM, Rob Landley <rob@landley.net> wrote:
> 
> On 4/11/20 1:12 AM, Finn Thain wrote:
>>> On Fri, 10 Apr 2020, Rob Landley wrote:
>>> 
>>> I'm adding m68k support to toybox's "make root" target and I have a 
>>> kernel and a rootfs.cpio.gz, but qemu's -initrd option doesn't put the 
>>> rootfs image somewhere the m68k kernel can find it.
>>> 
>>> Is this a "modify qemu" problem or a "modify kernel" problem?
>> 
>> It sounds more like a "modify kernel .config" problem. But it could be a 
>> regression; what versions of qemu and kernel did you try?
> 
> "Works for me", got it. I'll keep digging.
> 
> QEMU is the one Laurent Vivier maintains that's been out of tree for something
> like 12 years now, the default branch claims to be "q800-dev" and the last
> commit was in december. It still runs my old aboriginal linux system image from
> 2014 (boots to a shell prompt).

I think most of these things should be merged upstream these days but Laurent probably needs to correct me on what’s missing.

> Kernel is vanilla v5.6 with the arch configured with:
> 
> QEMU="m68k -M q800" KARCH=m68k KARGS=ttyS0 VMLINUX=vmlinux
> KCONF=MMU,M68040,M68KFPU_EMU,MAC,SCSI_MAC_ESP,MACINTOSH_DRIVERS,ADB,ADB_MACII,NET_CORE,MACSONIC,SERIAL_PMACZILOG,SERIAL_PMACZILOG_TTYS,SERIAL_PMACZILOG_CONSOLE
> 
> Which is top of:
> 
> BASE=EARLY_PRINTK,BINFMT_ELF,BINFMT_SCRIPT,NO_HZ,HIGH_RES_TIMERS,BLK_DEV,BLK_DEV_INITRD,RD_GZIP,BLK_DEV_LOOP,EXT4_FS,EXT4_USE_FOR_EXT2,VFAT_FS,FAT_DEFAULT_UTF8,MISC_FILESYSTEMS,SQUASHFS,SQUASHFS_XATTR,SQUASHFS_ZLIB,DEVTMPFS,DEVTMPFS_MOUNT,TMPFS,TMPFS_POSIX_ACL,NET,PACKET,UNIX,INET,IPV6,NETDEVICES,NET_CORE,NETCONSOLE,ETHERNET
> 
> As interpreted by:
> 
>  sed -E '/^$/d;s/([^,]*)($|,)/CONFIG_\1=y\n/g' <<< "$BASE,$KCONF > mini.conf
>  make ARCH=$KARCH allnoconfig KCONFIG_ALLCONFIG=mini.conf
>  make ARCH=$KARCH CROSS_COMPILE="$CROSS_COMPILE" -j $(nproc)
> 
> Plus of course:
> 
>  echo "qemu-system-$QEMU" '"$@"' -nographic -no-reboot -m 256 \
>       "-kernel $(basename "$VMLINUX") -initrd root.cpio.gz" \
>       "-append \"quiet panic=1 HOST=$TARGET console=$KARGS \$KARGS\"" \
>       ${DTB:+-dtb "$(basename "$DTB")"} > "$OUTPUT/qemu-$TARGET.sh"
> 
> I.E. the usual. (I'm trying to add m68k support to
> https://github.com/landley/toybox/blob/master/scripts/mkroot.sh which already
> boots armv5l, armv7l, aarch64, i486, i686, x86_64, mips, mipsel, powerpc, s390x,
> and sh4 to a shell prompt under qemu, although you still have to
> KARGS=rdinit=/bin/sh because I haven't QUITE got my new shell making it through
> the end of the init script. Should do in another couple days.)

Very cool. Thanks a lot for doing this!

Adrian