Re: QEMU CAN emulation (Kvaser PCI, SJA1000) - how to setup and run

[wojciech . st]

So I finally fonud the solution. 

All the described setup was OK. 

The problem was with BusyBox ip tool. I found on some formu to not use the BusyBox version and use the iproute2 tool instead. 

After I added the iprotue2 package in Buildroot config the example start working. 

Thanks

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Nov 12, 2020, 07:57 by wojciech.st@tutanota.com:

Hi

I would like to run QEMU with CAN emulation and check how does it work.
I focused on the following scenario:
Host Ubuntu 16.04 with vcan0 sends messages to QEMU x86_64 with Linux or vice versa. 

But I always get the same error while setting up the can0 on guest:
# ip link set can0 type can bitrate 1000000
ip: either "dev" is duplicate, or "type" is garbage

I build guest Linux with Buildroot and I tried multiple versions of kernel and QEMU to see if any works.
Since with the new Buildroot and QEMU I did not succeed I go as fare as Buildroot from 2016 to get kernel 3.9 (based on info from QEMU 5.1 docs/can.txt example) and 3.8 and see it it works but still get the same result.

So I come into conclusion that I am missing some crucial part or information to start this example.

I use the following setup:

In Buildroot to the default configuration qemu_x86_64_defconfig I usually add only the CAN drivers as modules in kernel configuration:

- <M> CAN bus subsystem support
    - <M> Raw CAN Protocol (raw access with CAN-ID filtering)
    - <M> Broadcast Manager CAN Protocol (with contest filtering)
    - <M> CAN Gateway/Router (with netlink configuration)
      - <M> Platform CAN drivers with Netlink support
      - CAN bit-timing calculation
      - <M> Philips/NXP SJA1000 devices
      - <M> Kvaser PCIcanx and Kvaser PCIcan PCI Cards
      - CAN devices debugging messages

or small twaks to strt on particular qemu version or configuration.

 Right now I focus on the following QEMU configration:

qemu-2.12.1/x86_64-softmmu/qemu-system-x86_64

    -M pc -m 4096M 
    -kernel buildroot-2016.11.3/output/images/bzImage
    -drive file=buildroot-2016.11.3/output/images/rootfs.ext2,if=virtio,format=raw
    -object can-host-socketcan,id=canhost0,if=can0,canbus=canbus0
    -device kvaser_pci,canbus=canbus0  
    -nographic
    -append "rootwait root=/dev/vda console=tty1 console=ttyS0"

On the host side (Ubuntu 16.04 VirtualBox and Native installation):

sudo ip link add dev can0 type vcan
sudo ip link set can0 up

On the QEMU guest side:

modprobe can-raw
modprobe kvaser-pci
ip link set can0 typ can bitrate 1000000

On the guest side after modprobing the drivers I see the can0 interface and no errors in dmesg but the setting up the interface with ip tool up ends with error.

I would be grateful for any comment or suggestions as I already run out of ideas.

 

Regards,

 

Wojciech

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