Re: [GIT PULL] New TPM driver and features

[Kent Yoder <key@linux.vnet.ibm.com>]

Hi,

On Thu, Jul 26, 2012 at 02:46:25PM -0700, H. Peter Anvin wrote:
> On 07/26/2012 07:31 AM, Kent Yoder wrote:
> >       hw_random: add support for the TPM chip as a hardware RNG source
> 
> Could you clarify this?  rngd (the user of /dev/hw_random) already
> has support for the TPM... is this fundamentally different (e.g. can
> it coexist with tcsd being in use at the same time)?

  These can coexist at the same time since /dev/tpm0 is only opened once
from user-space (from tcsd) and this hwrng driver comes in through the
kernel. There would be some amount of contention with the tpm, but its
not likely to be noticable - grabbing rng data doesn't require any state
in the tpm, like an auth session or key loading.

  Since the rngd support for the tpm requires trousers, this patch will
be useful in places where you don't want to have to deploy the full TSS,
like embedded and early boot.

Kent

> 
> 	-hpa
> 
> -- 
> H. Peter Anvin, Intel Open Source Technology Center
> I work for Intel.  I don't speak on their behalf.
>