Communication Processor Update Package

Updates to the communication processor are stored within a special CPUP package contained within Development kit (DEM or PDEL) PUP files.

In firmware .940 and .945 (and their subsets) exclusively, the CPUP are embedded within encrypted Update Packages.

CPUP Structure
Each CPUP shares a common header.

Every CP updates below version 1000 (found in firmware 1.00) are divided in 2 parts (2 distinct CPUP files sharing the same version value).

Every version after version 1000 is only comprised of a single part.

CP board id

 * DEM-300xH has the CP board id 3
 * PDEL-100x has the CP board id 4

CP version
Here are the different CP versions identified as of today:

Kernel Boot Loader logs
The Kernel Boot Loader and Non-secure Kernel Boot Loader respectively reference the current CP version in their bootlog (the version issued by KBL appears in the console output), this follows the below standard:

KBL:

NSKBL:

Where bid. is the Board id and ver. is the CP firmware version For example "bid.4 ver.1301" stands for board id 4, CP version 1301

in NSKBL format the information is logged in the following format: "0x00041301 [0x00041301]: CP bid & version" Where 0x0004 is the mask for bid (Board id 4) and 0x1301 is the mask for version (Version 1301).

These version information appear to most likely be read from sysroot at offset 0x44 (length u32 in little endian, 0x01130400 for bid.4 ver.1301, or 0x00041301 with the proper endianness)

psp2ctrl info
You can get additional information by using the sdk's psp2ctrl info command. Information is displayed as such:

DEM-3000H in normal mode

CP: BoardVersion: 3 PackageVersion: 0.9.6.0 RecoveryPackageVersion: 0.9.2.0 ProtocolVersion: 1.0.7.0 Flags: 0x0

DEM-3000H in recovery mode

CP: BoardVersion: 3 PackageVersion: 0.9.6.0 RecoveryPackageVersion: 0.9.2.0 ProtocolVersion: 1.0.5.0 Flags: 0x1

PDEL-1001 in normal mode

CP: BoardVersion: 4 PackageVersion: 1.3.0.1 RecoveryPackageVersion: 1.0.0.2 ProtocolVersion: 1.0.7.0 Flags: 0x0

PDEL-1001 in recovery mode CP: BoardVersion: 4 PackageVersion: 1.3.0.1 RecoveryPackageVersion: 1.0.0.2 ProtocolVersion: 1.0.7.0 Flags: 0x1

Note: The flag exposed in the above examples is the recovery mode flag, while the flag is set to 0x1, recovery mode is active and the CP is running from the recovery bank.

Update
The Communication Processor is updated through the use of the SceDeci4pCpup module.

Downgrade
The Communication Processor on PS Vita Development units is not downgradable within normal operations (even when downgrading the unit itself using a PUP). It may be possible to downgrade by using the psp2ctrl recover-cp cpupdate.bin command while in recovery mode where cpupdate.bin is a CPUP of a version equal or higher to the RecoveryPackageVersion, it may also be possible to downgrade from the vita side by patching or bypassing the version check performed by SceDeci4pCpup.

Recovery mode
In the event that the CP becomes unresponsive a special recovery mode exists, to enter this mode you need to press the "init" button (physically located at the bottom of the CP) while the AC is plugged in, the CP will then reboot into recovery mode (the led will turn blue, then green). If your unit is connected, you will get disconected from TM server until you reconnect the usb, you may still experience timeouts when running the psp2ctrl info command, if so your SDK binaries might not be compatible with the version used in the recovery bank and you may need to use older ones.

While in recovery mode, until the AC gets disconnected, the CP will be running its recovery package firmware, while this essentially acts as a downgrade, the version located in the active bank will not change, the version reported by the CP is not the running version but rather the version that's currently flashed in the normal/active bank, it is therefore not possible to downgrade a unit by updating to a PUP while in recovery mode because the version reported will still be higher than the CPUP present inside the PUP.

While this does not permanantly downgrades your CP firmware, this is however useful in the attempts of triggering a possible vulnerability that would have been patched on a later revision.