I was wondering about that.  The values returned from the TPM in the hp6930p are definitely milliseconds, they are in fact equal to the default values.

 

A possible solution would be to always use the minimum of the value returned from the TPM and the default value.  Presumably the reason for allowing the tpm to specify the timeout is to allow a slow TPM to specify longer timeouts.

 

     christian

 

From: Wang, Shane [mailto:shane.wang@intel.com]
Sent: Sunday, January 31, 2010 10:33 PM
To: Ross Philipson; tboot-devel@lists.sourceforge.net
Cc: Christian Limpach
Subject: RE: [tboot-devel] [PATCH] Fix timeout bug introduced by tboot.hg changeset 176.

 

Hi, Ross and Christian,

 

According to TCG PC Client Sepcific TPM Interface Specification (TIS), calling the TPM_GetCapability command with the capability TPM_CAP_PROP_TIS_TIMEOUTS return an array of uint32 values each representing the number of microseconds for the associated timeout. And the structure we used represents the number of milliseconds. I also tested the code with some TPMs. I guess maybe your hp6930p doesn't conform to the spec.

 

Thanks.

Shane

 


From: Ross Philipson [mailto:Ross.Philipson@citrix.com]
Sent: 2010
129 18:45
To: tboot-devel@lists.sourceforge.net
Cc: Christian Limpach
Subject: [tboot-devel] [PATCH] Fix timeout bug introduced by tboot.hg changeset 176.

Patch to fix timeout bug introduced by tboot.hg changeset 176. Either the TPM in the hp6930p doesn't operate to spec or the code was never tested.  With the patch, the values read from the tpm are equal to the default values used before tpm timeout code was added in changesets 163 and 176.

 

Signed-off-by: Christian Limpach christian.limpach@eu.citrix.com

Acked-by: Ross Philipson ross.philipson@citrix.com

 

 

diff -r 75e242a56344 tboot/common/tpm.c

--- a/tboot/common/tpm.c      Tue Jan 05 23:05:07 2010 -0800

+++ b/tboot/common/tpm.c      Fri Jan 29 00:59:05 2010 +0000

@@ -1944,10 +1944,10 @@

          * timeout_x represents the number of milliseconds for the timeout

          * and timeout[x] represents the number of microseconds.

          */

-        g_timeout.timeout_a = timeout[0]/1000;

-        g_timeout.timeout_b = timeout[1]/1000;

-        g_timeout.timeout_c = timeout[2]/1000;

-        g_timeout.timeout_d = timeout[3]/1000;

+        g_timeout.timeout_a = timeout[0];

+        g_timeout.timeout_b = timeout[1];

+        g_timeout.timeout_c = timeout[2];

+        g_timeout.timeout_d = timeout[3];

         printk("TPM timeout values: A: %u, B: %u, C: %u, D: %u\n",

                g_timeout.timeout_a, g_timeout.timeout_b, g_timeout.timeout_c,

                g_timeout.timeout_d);