Re: /dev/hwrng no such device

[Christopher Snowhill (kode54)]

On Feb 5, 2020, at 2:02 PM, Wesley Chow <address@hidden> wrote:



I'm building a kernel suitable to boot Raspbian and a custom buildroot based ARM OS via qemu-system-arm. Everything appears to work except for the hardware rng device. I'm using a virt machine with:

      -object rng-random,filename=/dev/urandom,id=rng0 -device virtio-rng-pci,rng=rng0

In both Raspbian and my own system, I see this:

# cat /dev/hwrng
cat: read error: No such device

rng-tools can not read the device and doesn't start up properly, leaving my entropy pool woefully low. The kernel I'm using is based off the rpi-4.19.y branch (4.19.97) with additional config options set. Of relevance:

CONFIG_PCI=y

CONFIG_VIRTIO=y
CONFIG_VIRTIO_PCI=y
CONFIG_VIRTIO_BLK=y
CONFIG_HW_RANDOM_VIRTIO=y
CONFIG_CRYPTO_DEV_VIRTIO=y
CONFIG_CRYPTO_HW=y
CONFIG_CRYPTO_RNG2=y
CONFIG_HW_RANDOM=y

I honestly don't know which of these actually matter. I'm wondering, am I missing something?

Thanks,

Wes

This is simply because not a single Raspberry Pi device has ever supported hardware crypto extensions. These are, simply put, tinkerer’s toys, not real computing devices.

Maybe have a look at the Rock Pi 4, which does support crypto extensions.