NAME

       tpm2_pcrreset(1) - Reset one or more PCR banks

SYNOPSIS

       tpm2_pcrreset [OPTIONS] PCR_INDEX ...

DESCRIPTION

       tpm2_pcrreset(1)  -  Reset  PCR  value  in all banks for specified index.  More than one PCR index can be
       specified.

       The reset value is manufacturer-dependent and is either sequence of 00 or FF on the length  of  the  hash
       algorithm for each supported bank.

       PCR_INDEX is a space separated list of PCR indexes to be reset when issuing the command.

OPTIONS

       This tool accepts no tool specific options.

       • --cphash=FILE

         File path to record the hash of the command parameters.  This is commonly termed as cpHash.  NOTE: When
         this option is selected, The tool will not actually execute the command, it simply returns a cpHash.

COMMON OPTIONS

       This collection of options are common to many programs  and  provide  information  that  many  users  may
       expect.

       • -h, --help=[man|no-man]: Display the tools manpage.  By default, it attempts to invoke the manpager for
         the tool, however, on failure will output a short tool summary.  This is the same behavior if the “man”
         option argument is specified, however if explicit “man” is requested, the tool will provide errors from
         man on stderr.  If the “no-man” option if specified, or the manpager fails, the short options  will  be
         output to stdout.

         To  successfully  use  the  manpages  feature  requires the manpages to be installed or on MANPATH, See
         man(1) for more details.

       • -v, --version: Display version information for this tool, supported tctis and exit.

       • -V, --verbose: Increase the information that the tool prints to the console during its execution.  When
         using this option the file and line number are printed.

       • -Q, --quiet: Silence normal tool output to stdout.

       • -Z,  --enable-errata:  Enable  the application of errata fixups.  Useful if an errata fixup needs to be
         applied to commands sent to the TPM.  Defining the environment TPM2TOOLS_ENABLE_ERRATA is equivalent.

       • -R, --autoflush: Enable autoflush for transient objects created by the command.  If a parent object  is
         loaded  from  a  context  file also the transient parent object will be flushed.  Autoflush can also be
         activated if the environment variable TPM2TOOLS_AUTOFLUSH is is set to yes or true.

TCTI Configuration

       The TCTI or “Transmission Interface” is the communication mechanism with the TPM.  TCTIs can  be  changed
       for communication with TPMs across different mediums.

       To control the TCTI, the tools respect:

       1. The command line option -T or --tcti

       2. The environment variable: TPM2TOOLS_TCTI.

       Note: The command line option always overrides the environment variable.

       The current known TCTIs are:

       • tabrmd  - The resource manager, called tabrmd (https://github.com/tpm2-software/tpm2-abrmd).  Note that
         tabrmd and abrmd as a tcti name are synonymous.

       • mssim - Typically used for communicating to the TPM software simulator.

       • device - Used when talking directly to a TPM device file.

       • none - Do not initalize a connection with the TPM.  Some tools  allow  for  off-tpm  options  and  thus
         support  not using a TCTI.  Tools that do not support it will error when attempted to be used without a
         TCTI connection.  Does not support ANY options and MUST BE presented as the exact text of “none”.

       The arguments to either the command line option or the environment variable are in the form:

       <tcti-name>:<tcti-option-config>

       Specifying an empty string for either the <tcti-name> or  <tcti-option-config>  results  in  the  default
       being used for that portion respectively.

   TCTI Defaults
       When a TCTI is not specified, the default TCTI is searched for using dlopen(3) semantics.  The tools will
       search for tabrmd, device and mssim TCTIs IN THAT ORDER and USE THE FIRST ONE FOUND.  You can query  what
       TCTI  will  be  chosen  as  the  default  by  using  the -v option to print the version information.  The
       “default-tcti” key-value pair will indicate which of the aforementioned TCTIs is the default.

   Custom TCTIs
       Any TCTI that implements the dynamic TCTI interface can be loaded.  The tools internally  use  dlopen(3),
       and the raw tcti-name value is used for the lookup.  Thus, this could be a path to the shared library, or
       a library name as understood by dlopen(3) semantics.

TCTI OPTIONS

       This collection of options are used to configure the various known TCTI modules available:

       • device: For the device TCTI, the TPM character device file for use by the device TCTI can be specified.
         The default is /dev/tpm0.

         Example: -T device:/dev/tpm0 or export TPM2TOOLS_TCTI=“device:/dev/tpm0”

       • mssim:  For  the mssim TCTI, the domain name or IP address and port number used by the simulator can be
         specified.  The default are 127.0.0.1 and 2321.

         Example: -T mssim:host=localhost,port=2321 or export TPM2TOOLS_TCTI=“mssim:host=localhost,port=2321”

       • abrmd: For the abrmd TCTI, the configuration string format is  a  series  of  simple  key  value  pairs
         separated by a `,' character.  Each key and value string are separated by a `=' character.

         • TCTI abrmd supports two keys:

           1. `bus_name' : The name of the tabrmd service on the bus (a string).

           2. `bus_type' : The type of the dbus instance (a string) limited to `session' and `system'.

         Specify the tabrmd tcti name and a config string of bus_name=com.example.FooBar:

                \--tcti=tabrmd:bus_name=com.example.FooBar

         Specify the default (abrmd) tcti and a config string of bus_type=session:

                \--tcti:bus_type=session

         NOTE: abrmd and tabrmd are synonymous.

EXAMPLES

   Reset a single PCR
              tpm2_pcrreset 23

   Reset multiple PCRs
              tpm2_pcrreset 16 23

NOTES

       On  operating  system’s  locality  (generally  locality 0), only PCR 23 can be reset.  PCR-16 can also be
       reset on this locality, depending on TPM manufacturers which could define this PCR as resettable.

       PCR 0 to 15 are not resettable (being part of SRTM).  PCR 16 to  22  are  mostly  reserved  for  DRTM  or
       dedicated to specific localities and might not be resettable depending on current TPM locality.

Returns

       Tools can return any of the following codes:

       • 0 - Success.

       • 1 - General non-specific error.

       • 2 - Options handling error.

       • 3 - Authentication error.

       • 4 - TCTI related error.

       • 5 - Non supported scheme.  Applicable to tpm2_testparams.

BUGS

       Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)

HELP

       See the Mailing List (https://lists.linuxfoundation.org/mailman/listinfo/tpm2)