Boot Sequence
Boot Process
Syscon
Syscon powers up and sets up DRAM, sets up boot context buffer, turns on the KERMIT SOC which eventually starts the Boot code on the CMeP Processor.
Boot ROM
The PS Vita main application processor is an ARM Cortex A9 MPcore. It implements ARM TrustZone for execution in both a non-secure world and a sandboxed Secure World. However it is not the first processor to run on boot.
The cmep processor is the actual secure boot device rather than the ARM processor. The cmep processor bootrom ("first loader") is the first known code running on PS Vita start. Once it starts it likely maps the eMMC and directly reads in the second_loader.enp from the eMMC (SLB2 partition) or SD Card (if SD BOOT challenge passes). This is in the native load format of the bootrom. There are 2 layers of encryption. First it decrypts the per-console layer that was added during the firmware installation. After that it decrypts the factory-encrypted layer then begins execution. See Enc.
The Second Loader is primarily responsible for preparing the ARM processor. It initializes DRAM and decrypts kernel_boot_loader.self from eMMC SLB2 partition into DRAM. It also writes the ARM exception vector and some boot context information to the 32kB scratch buffer (mirror mapped to 0x00000000 on ARM). kernel_boot_loader.self contains both the secure kernel bootloader and TrustZone, as well as the non-secure kernel bootloader. At this point the kprx_auth_sm.self and prog_rvk.srvk read from the eMMC SLB2 partition are both loaded into DRAM. Finally, the Second Loader resets itself with a pointer to the secure_kernel.enp or enp_ binary.
Cmep processor then restarts and loads the secure_kernel.enp in and again decrypts the per-console layer that was added during the firmware install, and the factory layer. At this point the cmep processor is prepared and Secure Kernel tells Syscon to reset the ARM CPU at 0x00000000 (cmep scratch buffer). This triggers the ARM secure boot process.
Secure Kernel Bootloader
The secure kernel bootloader decompresses the ARZL compressed TrustZone kernel, loads it and sets up the VBAR and MVBAR. It then decompresses the ARZL non-secure kernel bootloader, sets NS in SCR and jumps into non-secure kernel bootloader with svc mode. See Kernel Boot Loader for more information.
Non-secure Kernel Bootloader
The non-secure kernel bootloader contains an embedded and likely stripped version of SceSysmem, SceKernelModulemgr, SceSblSmschedProxy, and some other core drivers. The NSKBL sets up the eMMC device (again) and starts os0:psp2bootconfig.skprx.
ScePsp2BootConfig
This kernel module does not export any library. It only has a module init function that has a hard coded list of core kernel modules (ex: sysmem.skprx) which are loaded with calls back into NSKBL through SceKblForKernel imports. Once the core initialization is done, the next module to run is SceSysStateMgr.
FW 0.931 special case
On FW 0.931, NSKBL embeds the kernel modules list in data segment instead of using the ScePsp2BootConfig kernel module. Here is the list:
sysmem.skprx excpmgr.skprx intrmgr.skprx systimer.skprx acmgr.skprx threadmgr.skprx dmacmgr.skprx ssproxy.skprx smsc_proxy.skprx authmgr.skprx iofilemgr.skprx modulemgr.skprx processmgr.skprx backtrace.skprx sdbgsdio.skprx deci4p_sdfmgr.skprx deci4p_sttyp.skprx deci4p_sdbgp.skprx deci4p_sdrfp.skprx stdio.skprx lowio.skprx clockgen.skprx sdif.skprx sdstor.skprx fatsd.skprx exfatfs.skprx pamgr.skprx sysstatemgr.skprx
SceSysStateMgr
This kernel module also does not export any library. Its init function first maps all the SceKernelBootimage embedded modules and redirects them to os0:kd/. Then it decrypts os0:psp2config.skprx or os0:psp2config_vita.skprx or os0:psp2config_dolce.skprx and parses the System Configuration Script to load the remaining modules and finally either SceSafemode or SceShell or ScePsp2Swu or ScePsp2Diag.
Also refer to the SceSysStateMgr page for System Configuration Script.
Boot Partition
The boot partition is SLB2 formatted. It contains entries these files:
| Name | Earliest Known Version | Comments |
|---|---|---|
| kernel_boot_loader.self | 0.931 | Secure KBL and ARZL compressed NS KBL |
| kprx_auth_sm.self | 0.931 | Used with the cmep processor to decrypt SELFs |
| prog_rvk.srvk | 0.931 | SCE encrypted SELF revocation list |
| second_loader.enp | 0.931 | Secure bootloader |
| second_loader.enp_ | 0.931 | Related to second_loader.enp in some way, likely for encryption |
| secure_kernel.enp | 0.931 | Secure kernel loader |
| secure_kernel.enp_ | 0.931 | Related to secure_kernel.enp in some way, likely for encryption |
| secure_kernel.xxx | 0.931 | Prototype secure kernel loader encrypted differently than secure_kernel.enc |
Boot Debug Checkpoint Codes
During the boot sequence, the various bootloaders will update a GPIO register specifying the progress into boot. This can be used to debug where in the boot process something fails.
Second Loader checkpoint codes start at 0x40 (e.g. GPO value 0x52 corresponds to SBL code 0x12).
GPIO
The GPIO registers are registered at 0xE20A000C (turn off bits) and 0xE20A0008 (turn on bits). On PDEL units, this maps to the LED lights.
Known Codes
The Event column indicates what happens/is about to happen when a code is shown on the GPO LED. If boot of the unit doesn't succeed, the Halting event column indicates what caused the boot process to fail based on the last value of the GPO LED.
| Code | Location | Event | Halting event |
|---|---|---|---|
| 64 / 0x40 | second_loader (0.931) | SBL finished successfully | |
| 65 / 0x41 | second_loader | Some Hardware Info check complete - GPO intiailization OK? | |
| 66 / 0x42 | second_loader (0.931) | Something with Syscon | ERROR: communication with Syscon failed |
| 67 / 0x43 | second_loader | Register bigmac key 0x508 and 0x51B complete | ERROR: communication with Syscon failed |
| 68 / 0x44 | second_loader | ERROR: ?some check with keyring 0x501 and Cmep data? failed | |
| 69 / 0x45 | second_loader | ?Initializing LPDDR2? | ERROR: ?LPDDR2 initialization failed? |
| 70 / 0x46 | second_loader | Setting QA flags to bigmac keyring complete | |
| 71 / 0x47 | second_loader (0.931) | Calling testMemory
|
?ERROR: testMemory failed?
|
| 72 / 0x48 | second_loader (0.931) | ?Initializing SD/eMMC? | ERROR: ?SD/eMMC initialization failed? |
| 73 / 0x49 | second_loader (0.931) | ?Loading kernel_boot_loader.self?
|
ERROR: ?reading/loading/... kernel_boot_loader.self failed?
|
| 74 / 0x4A | second_loader (0.931) | ERROR: ?SD/eMMC I/O error? | |
| 75 / 0x4B | second_loader (0.931) | WARNING: Reading ConsoleID from eMMC failed | |
| 76 / 0x4C | second_loader (0.931) | ERROR: ?starting ARM clock failed? (cannot happen on FW 0.931) | |
| 77 / 0x4D | second_loader (0.931) | ?Initializing SNVS? | ERROR: Writing 0x502-0x504/0x50B/... keyring failed (?SNVS init failed?) (cannot happen on FW 0.931) |
| 78 / 0x4E | second_loader (0.931) | ERROR: SBL version mismatch with SVNS-stored firmware version | |
| 79 / 0x4F | second_loader (0.931) | ERROR: testMemory failed (dummy in 0.931, cannot happen)
| |
| 80 / 0x50 | second_loader (0.931) | Copying keyrings 0x602/0x601 to physical address 0xE0020100/0xE0020200 | |
| 82 / 0x52 | second_loader | ERROR: eMMC is not available | |
| 83 / 0x53 | second_loader | WARNING: Reading OpenPSID from eMMC failed | |
| 84 / 0x54 | second_loader | ERROR: Minimal firmware read failed / SBL version is lower than minimal firmware | |
| 85 / 0x55 | second_loader | Setting factory firmware version to Bigmac keyring complete | WARNING: Something related to Syscon communication failed? |
| 86 / 0x56 | second_loader | ||
| 87 / 0x57 | second_loader (0.931) | WARNING: ??? | |
| 88 / 0x58 | second_loader (0.940) | WARNING: invalid/mismatched per-console information? | |
| 89 / 0x59 | second_loader (0.931) | WARNING: ??? | |
| 90 / 0x5A | second_loader | About to write SceKblParam to SPAD32K | |
| 94 / 0x5E | second_loader (0.931) | ERROR: SVNS-stored firmware version is lower than minimal firmware | |
| 96 / 0x60 | second_loader | Setting SceKblParam complete and Start setting some device clock. | |
| 129 / 0x81 | Secure Kernel BootLoader | Core 0 (secure world) pre-init complete | |
| 130 / 0x82 | Secure Kernel BootLoader | Secure world interrupts registered (?) | |
| 131 / 0x83 | Secure Kernel BootLoader | Serial console ready, boot message printed | |
| 132 / 0x84 | Secure Kernel BootLoader | Some device init | |
| 133 / 0x85 | Secure Kernel BootLoader | Some co-processor init. Starting point for other cores. | |
| 134 / 0x86 | Secure Kernel BootLoader | MMU enabled, VBAR/MVBAR set up | |
| 135 / 0x87 | Secure Kernel BootLoader | Nothing since 134 | |
| 136 / 0x88 | Secure Kernel BootLoader | Boot setup complete, secure kernel loading begin | |
| 137 / 0x89 | Secure Kernel BootLoader | Secure kernel loaded. About to load NS KBL at 0x51000000
|
|
| 138 / 0x8A | Secure Kernel BootLoader | Secure kernel loaded. About to resume context at 0x1F000000.
|
ERROR: Undefined Instruction exception |
| 139 / 0x8B | Secure Kernel BootLoader | ERROR: SVC exception (should not happen) | |
| 140 / 0x8C | Secure Kernel BootLoader | ERROR: Prefetch abort exception | |
| 141 / 0x8D | Secure Kernel BootLoader | ERROR: Data abort exception | |
| 142 / 0x8E | Secure Kernel BootLoader | ERROR: IRQ exception (should not happen) | |
| 143 / 0x8F | Secure Kernel BootLoader | ERROR: FIQ exception (should not happen) | |
| 161 / 0xA1 | Non-Secure Kernel BootLoader | Core 0 (non-secure world) pre-init complete | |
| 162 / 0xA2 | Non-Secure Kernel BootLoader | Some interrupts registered (?) | |
| 163 / 0xA3 | Non-Secure Kernel BootLoader | Serial console ready, boot message printed (if enabled) | |
| 164 / 0xA4 | Non-Secure Kernel BootLoader | Some buffer is initialized to device addresses | |
| 165 / 0xA5 | Non-Secure Kernel BootLoader | Some co-processor init. Starting point for other cores. | |
| 166 / 0xA6 | Non-Secure Kernel BootLoader | MMU enabled, VBAR set up | |
| 167 / 0xA7 | Non-Secure Kernel BootLoader | Nothing since 166 | |
| 168 / 0xA8 | Non-Secure Kernel BootLoader | Boot setup complete, NS kernel loading begin | |
| 169 / 0xA9 | Non-Secure Kernel BootLoader | Kernel pre-init (setup stacks, interrupts, etc) done. Right before first external loading. | |
| 170 / 0xAA | Non-Secure Kernel BootLoader | ERROR: Undefined Instruction exception | |
| 171 / 0xAB | Non-Secure Kernel BootLoader | ERROR: SVC exception (should not happen) | |
| 172 / 0xAC | Non-Secure Kernel BootLoader | ERROR: Prefetch abort exception | |
| 173 / 0xAD | Non-Secure Kernel BootLoader | ERROR: Data abort exception | |
| 174 / 0xAE | Non-Secure Kernel BootLoader | ERROR: IRQ exception (should not happen) | |
| 175 / 0xAF | Non-Secure Kernel BootLoader | ERROR: FIQ exception (should not happen) |
Suspend and Resume
Upon suspension, context is written to memory and a syscon command is issued to save the context pointer as well as other information (for example, if it should restart into update mode). When resuming, the boot process is the same as cold boot up until the secure kernel bootloader. After secure kernel loads, instead of decompressing and jumping to the non-secure kernel bootloader, it restores the saved context and returns to the kernel resume code.
See also Suspend.