On Fri, Mar 29, 2019 at 05:30:11PM +0100, Laurent Vivier wrote:
> If the device is not ready to provide data the kernel will
> be stuck indefinitely in the init function.
>
> This is not a problem if the device is driven using a module,
> but if the driver is linked directly into the kernel then the
> kernel boot sequence hangs.
>
> This can happen with virtio-rng device with rng-egd backend
> with no data provider, for instance with QEMU command line parameters:
>
> ...
> -chardev socket,id=charrng0,host=localhost,port=2345,server,nowait \
> -object rng-egd,id=objrng0,chardev=charrng0 \
> -device virtio-rng-pci,rng=objrng0,id=rng0
>
> To avoid that, we can call rng_get_data() in non blocking mode because
> the function already manages the case where byte_read is
> 0 (if the device is not already initialized).
>
> See also commit d3cc7996473a
> ("hwrng: fetch randomness only after device init")
>
> Signed-off-by: Laurent Vivier <lvivier@xxxxxxxxxx>
I think this is either not a bug (make sure that the user supplies
a RNG source) or it should be addressed in virtio-rng.
Cheers,
--
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
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