How to enable a shared directory between the booted guest OS on Morello FVP and the host linux machine

Hi, 

the latest Dec 2020 maintenance release now includes support for virtio_p9 - however I'm still having some issues, and have missed something obvious ... I tried Poky by (appropriately setting -C board.virtio_p9.root_path=/home/morello/SHARED in run_model.sh) and running the command below after a fresh install of FVP and rebuilding the board support. 

./run-scripts/run_model.sh -m ~/FVP_Morello/models/Linux64_GCC-6.4/FVP_Morello -f poky

then after boot and log in to the model ...

root@morello-fvp:~# mount -t 9p -o trans=virtio,version=9p2000.L FM /mnt/HOST
[ 646.303364] 9pnet_virtio: no channels available for device FM
mount: mounting FM on /mnt/HOST failed: No such file or directory

My host (ubuntu20.04.1 LTS) lsmod | grep virtio
9pnet_virtio 20480 0
9pnet 81920 2 9p,9pnet_virtio
virtio_input 16384 0

Thanks,

Andy

Hi, 

the latest Dec 2020 maintenance release now includes support for virtio_p9 - however I'm still having some issues, and have missed something obvious ... I tried Poky by (appropriately setting -C board.virtio_p9.root_path=/home/morello/SHARED in run_model.sh) and running the command below after a fresh install of FVP and rebuilding the board support. 

./run-scripts/run_model.sh -m ~/FVP_Morello/models/Linux64_GCC-6.4/FVP_Morello -f poky

then after boot and log in to the model ...

root@morello-fvp:~# mount -t 9p -o trans=virtio,version=9p2000.L FM /mnt/HOST
[ 646.303364] 9pnet_virtio: no channels available for device FM
mount: mounting FM on /mnt/HOST failed: No such file or directory

My host (ubuntu20.04.1 LTS) lsmod | grep virtio
9pnet_virtio 20480 0
9pnet 81920 2 9p,9pnet_virtio
virtio_input 16384 0

Thanks,

Andy

As far as I know, neither TF-A's FDT nor edk2-platform's DSDT include a description for the device and so the OS does not know it exists. You could try patching your TF-A's morello-fvp.dts to include it based on developer.arm.com/.../Morello-Platform-Model-notes-and-limitations. 

Hi Andy,

To enable and use the virtio P9 device you need to follow the steps below:

1- Enable the following kernel build flags.

CONFIG_NET_9P
CONFIG_NET_9P_VIRTIO
CONFIG_9P_FS
CONFIG_9P_FS_POSIX_ACL
CONFIG_9P_FSCACHE
CONFIG_9P_FS_SECURITY

2 - Add the following configuration to your DTS:

virtio_p9@1c1A0000 {
        compatible = "virtio,mmio";
        reg = <0x0 0x1c1a0000 0x0 0x200>;
        interrupts = <GIC_SPI 103 IRQ_TYPE_LEVEL_HIGH>;
};

3 - Rebuild everything

4 - Follow the instructions on how to use the virtio P9 located in the Fast Models Reference Manual 11.13

I hope this helps!

Regards,

Mauricio

Hi,

apologies - it's my first time delving into FVPs into any detail, so I'd appreciate a few more pointers if you can spare the time ...

STEP 1 - are talking about the host linux, or the guest linux hosted via the FVP? 

STEP 2 ...

I'm using instructions from https://git.morello-project.org/morello/docs/-/blob/morello/mainline/user-guide.rst

Given that it is bitbake based ... then I need to do something like?

 devtool modify trusted-firmware-a

Add the appropriate DTS configuration to  dtsi file(s)  in the trusted-firmware-a tree, any pointers on which one(s)?

STEP 3

bitbake trusted-firmware-a

bitbake core-image-minimal

STEP 4 seems clear - is chmod 777 myHostLinuxDirectory

still required for the host linux directory that is pointed to by the root_path configuration parameter passed to the FVP? 

On the FVP, after trying out these steps, I get the same error as before ...

Also using

find /proc/device-tree/ -type f -exec head {} + | grep virtio

to determine if the virtio_p9 is loaded,  ... so far no luck ... despite a few attempts.

Thanks,

Andy

Hi Andy,

Apologies for my brief summary on how to enable the virtio_p9. The changes are only applied to the guest OS, the one running on the FVP. Please follow the steps below under the morello_workspace poky directory structure:

1 - Add the build kernel flags below to <path to workspace>morello_workspace/bsp/build-poky/tmp-poky/work/morello_fvp-poky-linux/linux-yocto/5.4.51+gitAUTOINC+caafbdfe38_fed60f1c8e-r0/defconfig

CONFIG_NET_9P=y
CONFIG_NET_9P_VIRTIO=y
CONFIG_9P_FS=y
CONFIG_9P_FS_POSIX_ACL=y
CONFIG_PCI=y
CONFIG_VIRTIO_PCI=y
CONFIG_9P_FSCACHE=y
CONFIG_9P_FS_SECURITY=y

2 - Add the virtio_p9 configuration shown below to <path to workspace>morello_workspace/bsp/build-poky/tmp-poky/work/morello_fvp-poky-linux/trusted-firmware-a/1.0+gitAUTOINC+746e7e322f-r0/git/fdts/morello-fvp.dts

virtio_p9@1c1A0000 {
        compatible = "virtio,mmio";
        reg = <0x0 0x1c1a0000 0x0 0x200>;
        interrupts = <GIC_SPI 103 IRQ_TYPE_LEVEL_HIGH>;
};

3 - Recompile TFA:

      bitbake trusted-firmware-a -C compile

4 - Recompile linux-yocto:

     bitbake linux-yocto -C compile

5 - Recreate the images: (You might get a few warnings showing that some tfa and linux have been modified)

    bitbake core-image-minimal

6 - Add to <path to workspace>morello_workspace/run-scripts/run_model.sh the following model parameter (at around line 371)

  -C "board.virtio_p9.root_path=$PWD/shared_folder"

7 - Before launching the model create a folder on the host named shared_folder

  mkdir <path to workspace>morello_workspace/shared_folder

  **On the morello_workspace you should have the following folders: bsp docs run-scripts shared_folder

8 - Launch the model

  ./run-scripts/run_model.sh -m <path to fvp executable> -f poky

9 - On the model, when Poky finishes booting, log in as root and on the guest terminal, create and mount the shared folder as follows:

  mkdir shared_folder

  mount -t 9p -o trans=virtio,version=9p2000.L FM shared_folder

10 - Try to create a file from the guest terminal on the shared_folder and then reading it from the host shared folder. Try the other way round.

Although this might not be the optimal solution, I have made it work on a poky build.

I hope this temporary solution helps for now while we're looking into adding it to the repository.

Best regards,

Mauricio

Many many thanks, that was very easy to follow first time. For the benefit of others -  a minor thing, if you've executed a

devtool modify trusted-firmware-a

then you will obviously need to update the dts file ... something like

<morello workspace>/bsp/build-poky/workspace/sources/trusted-firmware-a/fdts/morello-fvp.dts