Re: [PATCH] libxl: fix matching of generic virtio device

[Oleksandr Tyshchenko <olekstysh@xxxxxxxxx>]

On 30.03.23 10:35, Viresh Kumar wrote:


Hello Viresh


> The strings won't be an exact match, and we are only looking to match
> the prefix here, i.e. "virtio,device". This is already done properly in
> libxl_virtio.c file, lets do the same here too.
>
> Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>

It feels to me this patch wants to gain the following tag:

Fixes: 43ba5202e2ee ("libxl: add support for generic virtio device")



> ---
>   tools/libs/light/libxl_arm.c | 12 ++++++++----
>   1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/tools/libs/light/libxl_arm.c b/tools/libs/light/libxl_arm.c
> index ddc7b2a15975..97c80d7ed0fa 100644
> --- a/tools/libs/light/libxl_arm.c
> +++ b/tools/libs/light/libxl_arm.c
> @@ -1033,10 +1033,14 @@ static int make_virtio_mmio_node_device(libxl__gc *gc, 
> void *fdt, uint64_t base,
>       } else if (!strcmp(type, VIRTIO_DEVICE_TYPE_GPIO)) {
>           res = make_virtio_mmio_node_gpio(gc, fdt);
>           if (res) return res;
> -    } else if (strcmp(type, VIRTIO_DEVICE_TYPE_GENERIC)) {
> -        /* Doesn't match generic virtio device */
> -        LOG(ERROR, "Invalid type for virtio device: %s", type);
> -        return -EINVAL;
> +    } else {
> +        int len = sizeof(VIRTIO_DEVICE_TYPE_GENERIC) - 1;
> +
> +        if (strncmp(type, VIRTIO_DEVICE_TYPE_GENERIC, len)) {
> +            /* Doesn't match generic virtio device */
> +            LOG(ERROR, "Invalid type for virtio device: %s", type);
> +            return -EINVAL;
> +        }

I agree that now code is aligned with what we have in libxl_virtio.c 
file, but I am afraid I cannot connect the sentence from the commit 
description:
"The strings won't be an exact match, and we are only looking to match
the prefix here, i.e. "virtio,device"."

with the sentence from docs/man/xl.cfg.5.pod.in:

"For generic virtio devices, where we don't need to set special or 
compatible properties in the Device Tree, the type field must be set to 
"virtio,device"."
I might miss something, but shouldn't we clarify the documentation?



>       }
>   
>       return fdt_end_node(fdt);