Re: [Qemu-devel] [RFC 00/13] hw/m68k: add Apple Machintosh Quadra 800 machine

[Thomas Huth]

On 09.06.2018 16:25, Philippe Mathieu-Daudé wrote:
> Hi Laurent,
> 
> On 06/08/2018 05:05 PM, Laurent Vivier wrote:
>> if you want to test the machine, I'm sorry, it doesn't boot
>> a MacROM, but you can boot a linux kernel from the command line.
>>
>> You can install your own disk using debian-installer, with:
>>
>>     ...
>>     -M q800 \
>>     -serial none -serial mon:stdio \
>>     -m 1000M -drive file=m68k.qcow2,format=qcow2 \
>>     -net nic,model=dp83932,addr=09:00:07:12:34:57 \
>>     -append "console=ttyS0 vga=off" \
>>     -kernel vmlinux-4.15.0-2-m68k \
>>     -initrd initrd.gz \
>>     -drive file=debian-9.0-m68k-NETINST-1.iso \
>>     -drive file=m68k.qcow2,format=qcow2 \
>>     -nographic
>>
>> If you use a graphic adapter instead of "-nographic", you can use "-g" to 
>> set the
>> size of the display (I use "-g 1600x800x24").
>>
>> You can get the ISO from:
>>
>> https://cdimage.debian.org/mirror/cdimage/ports/9.0/m68k/iso-cd/debian-9.0-m68k-NETINST-1.iso
>>
>> and extract the kernel and initrd.gz:
>>
>> guestfish --add debian-9.0-m68k-NETINST-1.iso --ro \
>>           --mount /dev/sda:/ <<_EOF_
>> copy-out /install/cdrom/initrd.gz .
>> copy-out /install/kernels/vmlinux-4.15.0-2-m68k .
>> _EOF_
> 
> Running with -d in_asm,int I get:
> 
> ----------------
> IN: nf_get_id
> 0x0000d432:  movel %a3,%d0
> 0x0000d434:  addil #0,%d0
> 0x0000d43a:  movel %d0,address@hidden
> 0x0000d43c:  jsr 0xd404
> 
> ----------------
> IN:
> 0x0000d404:  071400
> 
> INT      1: Unassigned(0xf4) pc=0000d404 sp=00393e60 sr=2700
> INT      2: Access Fault(0x8) pc=00000000 sp=00393e58 sr=2700
>             ssw:  00000506 ea:   00000000 sfc:  5    dfc: 5
> 
> ----------------
> IN:
> 0x0000280c:  clrl address@hidden
> 0x0000280e:  pea 0xffffffffffffffff
> 0x00002812:  movel %d0,address@hidden
> 0x00002814:  moveml %d1-%d5/%a0-%a2,address@hidden
> 0x00002818:  movel %sp,%d0
> 0x0000281a:  andil #-8192,%d0
> 0x00002820:  moveal %d0,%a2
> 0x00002822:  moveal %a2@,%a2
> 0x00002824:  movel %sp,address@hidden
> 0x00002826:  bsrl 0x557c
> 
> ----------------
> IN: buserr_c
> 0x0000557c:  subql #4,%sp
> 0x0000557e:  moveml %d2-%d7/%a3-%fp,address@hidden
> 0x00005582:  moveal %sp@(48),%a3
> 0x00005586:  btst #5,%a3@(44)
> 0x0000558c:  bnes 0x5592
> 
> ...
> 
> ----------------
> IN: panic
> 0x0002c956:  moveal 0x39503c,%a0
> 0x0002c95c:  moveq #101,%d1
> 0x0002c95e:  subql #1,%d1
> 0x0002c960:  bnes 0x2c9c6
> 
> objdump -S gives:
> 
> 0000d404 <nf_get_id_phys>:
>     d404:       7300            mvsb %d0,%d1
>     d406:       4e75            rts
> 
> Instruction which exists in the disas code, but doesn't seem
> tcg-implemented:
> 
> disas/m68k.c:3654:{"mvsb", 2,   one(0070400),   one(0170700), "*bDd",
> mcfisa_b },

0x7300 is the illegal opcode that is used by the Aranym emulator for its
"Native Feature" (some kind of Hypercall) interface:

https://github.com/aranym/aranym/wiki/natfeats-proposal#special-opcodes

It's also a valid opcode in the ColdFire ISA (that's why the
disassembler detects this as valid instruction), but the name of the
function (nf_get_id_phys) clearly indicates that Linux is trying to use
the Natfeats opcode here.

So it's normal that this opcode is not implemented in QEMU 680x0 mode.
If Linux correctly catches the illegal opcode exception afterwards,
everything is fine and you don't need to worry about this anymore.
However, if Linux fails to catch it correctly, there is certainly
something wrong here...

 Thomas