Re: [PATCH] hw/i386: pass RNG seed to e820 setup table

[Daniel P . Berrangé]

On Thu, Jun 30, 2022 at 01:37:17PM +0200, Jason A. Donenfeld wrote:
> Tiny machines optimized for fast boot time generally don't use EFI,
> which means a random seed has to be supplied some other way, in this
> case by the e820 setup table, which supplies a place for one. This
> commit adds passing this random seed via the table. It is confirmed to
> be working with the Linux patch in the link.

IIUC, this approach will only expose the random seed when QEMU
is booted using -kernel + -initrd args.

I agree with what you say about most VMs not using UEFI right now.
I'd say the majority of general purpose VMs are using SeaBIOS
still. The usage of -kernel + -initrd, is typically for more
specialized use cases. 

IOW, exposing random seed via the setup table feels like it'll
have a somewhat limited benefit.

Can we get an approach that exposes a random seed regardless of
whether using -kernel, or seabios, or uefi, or $whatever firmware ?

Perhaps (ab)use 'fw_cfg', which is exposed for any x86 VM no matter
what config it has for booting ?

With regards,
Daniel
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