virtio rpmsg probe error on Linux guest

[Edward Shao]

Hi Xvisor community,

I read "Inter-Guest Communication" page in the slides of Xvisor GENIVI Summit 2018.

It is very interesting.

I followed "docs/arm/bcm2837-raspi3.txt" to set up an environment on raspberry pi3.

I could boot two Linux guests normally.

When I started to try VirtIO RPMSP, I found an error in dmesg.

[guest0/uart0] [    1.096160] virtio_rpmsg_bus: probe of virtio3 failed with error -12

-12 means -ENOMEM.

The Linux guest kernel version is 4.15.0

I tried to trace the Linux kernel source and found the error came from

https://elixir.bootlin.com/linux/v4.15/source/drivers/rpmsg/virtio_rpmsg_bus.c#L923

bufs_va = dma_alloc_coherent(vdev->dev.parent->parent,total_buf_space, &vrp->bufs_dma,GFP_KERNEL);

It failed to allocate memory from "grandfather" device and the "total_buf_space" is 262144 (256KB).

I am not familiar with that part.

Any suggestions?

Best regards,

Edward

[Anup Patel]

Hi Edward,

This requires a fix in Linux RPMSG driver.

The first Linux fix was sent-out by me more than a year back but Linux
Remoteproc and RPMSG maintainers wanted to fix it differently so Loic
has patch series.

Here's Loic's patch:
https://patchwork.kernel.org/patch/10705343/

For the time being, you can just apply the patch manually on
Linux-4.15. I hope Loic-s patch will be merged soon.

Regards,
Anup

[Edward Shao]

Hi Anup,

After applying the patch, the error is gone.

Thanks for your help.

Best regards,

Edward

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