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tpm2_pcrreset(1)	    General Commands Manual	      tpm2_pcrreset(1)

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 is-
       suing the command.

OPTIONS
       This tool accepts no tool specific options.

       • --cphash=FILE

	 File path to record the hash of the command parameters.  This is com-
	 monly 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 in-
       formation 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 re-
	 quested, the tool will	provide	errors from man	 on  stderr.   If  the
	 "no-man"  option  if  specified, or the manpager fails, the short op-
	 tions 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.

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 vari-
       able.

       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  simula-
	 tor.

       • 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  respective-
       ly.

   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	 indi-
       cate 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 li-
       brary 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="de-
	 vice:/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_TC-
	 TI="mssim:host=localhost,port=2321"

       • abrmd:	 For  the abrmd	TCTI, the configuration	string format is a se-
	 ries 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.ex-
	 ample.FooBar:

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

	 Specify the default (abrmd) tcti and a	config string of bus_type=ses-
	 sion:

		\--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/listin-
       fo/tpm2)

tpm2-tools						      tpm2_pcrreset(1)

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