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<div class="moz-cite-prefix">On 09/29/2015 04:45 AM, Nikunj A
Dadhania wrote:<br>
</div>
<blockquote cite="mid:87612ttxzo.fsf@abhimanyu.in.ibm.com"
type="cite">
<pre wrap="">
Hi Stefan,
Stefan Berger <a class="moz-txt-link-rfc2396E" href="mailto:stefanb@linux.vnet.ibm.com"><stefanb@linux.vnet.ibm.com></a> writes:
</pre>
<blockquote type="cite">
<pre wrap="">The following series of patches adds TPM support to SLOF.
In particular it adds the following:
- TPM drivers for hardware interface and CRQ interface
- TPM initialization
- TPM logging area and firmware API to transfer it to the OS
(measurements are visible in sysfs)
- Some measurement code (Static Core Root Of Trust)
- TPM menu (accessible via 't' key during boot if TPM is available)
- Firmware API extensions following Power Firmware Doc
(to make trusted grub work)
</pre>
</blockquote>
<pre wrap="">
How much impact does this have on the boot time of the guest? Can you
share some measurements with and without this patches.</pre>
</blockquote>
<br>
I conducted the following 3 tests with 5 starts of QEMU each. I
measured the startup time (in seconds) using a stop watch from the
point QEMU started until the login prompt appeared on the console.
The Linux kernel did not have a built-in vTPM driver, so there is no
additional time spent interacting with the vTPM on this level.<br>
<br>
<font face="monospace">1) SLOF without patches applied, no attached
vTPM: 18.8, 18.3, 18.9, 18.9, 18.7<br>
2) SLOF with patches applied, no attached vTPM: 18.5, 18.7,
18.8, 18.6, 18.9<br>
3) SLOF with patches applied, and attached vTPM: 21.8, 21.7,
20.4, 21.2, 22.9<br>
</font><br>
Comments:<br>
<br>
2) SLOF with patches applied and no attached vTPM probes for an
attached vTPM and since it did not find one, it will not spend time
interacting with it.<br>
<br>
3) SLOF with patches applied and an attached vTPM will interact with
the vTPM; initialization of the vTPM also involves testing of crypto
algorithms and further interaction with the TPM accounts for the
additional time spent.<br>
<br>
Regards,<br>
Stefan<br>
<br>
<br>
<blockquote cite="mid:87612ttxzo.fsf@abhimanyu.in.ibm.com"
type="cite">
<pre wrap="">
</pre>
<blockquote type="cite">
<pre wrap="">
Necessarily, some of its parts are written in Forth, many are written
in 'C'. The extensions are known to work with QEMU for ppc64 running Linux.
Patches 4-6 will eventually need to be merged to avoid compiler warnings
related to unused functions.
Regards,
Stefan
</pre>
</blockquote>
<pre wrap="">
Regards,
Nikunj
</pre>
</blockquote>
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