Mailing List Archive

XEN ARM dt passthrough
Hi,

I'm trying to follow this guide to passthrough a device tree device.
https://xenbits.xen.org/docs/unstable/misc/arm/passthrough.txt

The device doesn't have an IOMMU thus I've enabled
xen,force-assign-without-iommu
In the guest dts but when I create the VM I get the following message.

user@imx8mpnavq:~/guest$ sudo xl create domU_test
Parsing config from domU_test
libxl: error: libxl_create.c:1135:libxl__domain_config_setdefault: passthrough not supported on this platform

failed to free memory for the domain

How do I enable the support for passthrough for my ARM based platform?

Yours sincerely,

Peter van der Perk
Re: XEN ARM dt passthrough [ In reply to ]
On 21/02/2023 09:43, Peter van der Perk wrote:
> Hi,

Hello,

> I'm trying to follow this guide to passthrough a device tree device.
> https://xenbits.xen.org/docs/unstable/misc/arm/passthrough.txt
>
> The device doesn't have an IOMMU thus I've enabled
> xen,force-assign-without-iommu
> In the guest dts but when I create the VM I get the following message.

The property xen,force-assign-without-iommu is to be used for dom0less
domain. When a domain is created by xl...

>
> user@imx8mpnavq:~/guest$ sudo xl create domU_test
> Parsing config from domU_test
> libxl: error: libxl_create.c:1135:libxl__domain_config_setdefault: passthrough not supported on this platform

... you want to avoid specifying "dtdev" in the configuration file.

Note that this device passthrough without an IOMMU only work with the
device is not DMA-capable.

If it is DMA-capable, then you will need to direct-map the domain and
there will no isolation.

Cheers,

--
Julien Grall