linux-kernel - Re: tpm_tis TPM2.0 not detected on cold boot

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Message-ID: <20190103132737.GD10491@linux.intel.com>
Date:   Thu, 3 Jan 2019 15:27:37 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Michael Niewöhner <linux@...ewoehner.de>
Cc:     Mimi Zohar <zohar@...ux.ibm.com>,
        James Bottomley <James.Bottomley@...senPartnership.com>,
        peterhuewe@....de, jgg@...pe.ca, arnd@...db.de,
        linux-integrity@...r.kernel.org,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Nayna Jain <nayna@...ux.ibm.com>,
        Ken Goldman <kgold@...ux.ibm.com>
Subject: Re: tpm_tis TPM2.0 not detected on cold boot

On Sun, Dec 23, 2018 at 12:55:12PM +0100, Michael Niewöhner wrote:
> There is another issue but I don't know if both are related. Maybe that's just a
> timing issue...
> 
> root@...ian:~# dd if=/dev/hwrng bs=1 count=1
> dd: error reading '/dev/hwrng': Operation not permitted
> 0+0 records in
> 0+0 records out
> 0 bytes copied, 0.755958 s, 0.0 kB/s
> root@...ian:~# dd if=/dev/hwrng bs=1 count=1 | xxd; dd if=/dev/hwrng bs=1
> count=1 | xxd
> dd: error reading '/dev/hwrng': Operation not permitted
> 0+0 records in
> 0+0 records out
> 0 bytes copied, 0.755697 s, 0.0 kB/s
> 1+0 records in
> 1+0 records out
> 00000000: 52                                       R
> 1 byte copied, 0.0106268 s, 0.1 kB/s
> 
> 
> Michael

What does /sys/devices/virtual/misc/hw_random/rng_current show?

Did run commands as a sanity check on my laptop and seem to work.

/Jarkko