Ernie
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The Syscon is responsible for handling button input (including power button), and contains non-volatile memory for storing system flags (mostly encrypted and signed). For example Kiosk flag is stored here. Syscon is also responsible for maintaining the physical address to the resume buffer during Suspend. Communication between Kermit and Syscon is mainly through SPI (see SceSyscon) but there are also some GPIO pins connecting the two.
Boot Process
The following is logged from boot. The timestamp is in seconds (the starting time is irrelevant). The arrow at the start indicates direction: '>' means Kermit to Syscon (MOSI) and '<' means Syscon to Kermit (MISO). Then there is a 2 byte command id or response code, followed by the payload, a checksum byte, and an (for only responses) unknown byte. Please note that the packets are listed in transfer order but this may not represent the logical order of the packets. It is currently unknown what the logical order should be, but one can guess that a response is "close to" a request.
First some version information seems to be sent from Syscon to Kermit. This is same for cold boot and resume boot.
< [2.048118000000000] 0x0004, flags=00, payload=[0D 06 00 01 | ....], chk=0xE1, unk=0x00 > [2.048118000000000] 0x0001, payload=[ | ], chk=0xFD < [2.048659583333333] 0x0004, flags=00, payload=[00 60 40 00 | .`@.], chk=0x55, unk=0x00 > [2.048659583333333] 0x0005, payload=[ | ], chk=0xF9 < [2.049330083333333] 0x0004, flags=00, payload=[32 30 31 32 31 31 30 38 31 37 30 34 | 201211081704], chk=0x92, unk=0x00 > [2.049330083333333] 0x0002, payload=[ | ], chk=0xFC < [2.054004333333333] 0x0004, flags=80, payload=[ | ], chk=0x79, unk=0x30 > [2.054004333333333] 0x0080, payload=[12 00 | ..], chk=0x6A < [2.058172916666666] 0x0024, flags=00, payload=[ | ], chk=0xD9, unk=0x30 > [2.058172916666666] 0x0000, payload=[ | ], chk=0xFE < [2.062716333333333] 0x0024, flags=00, payload=[ | ], chk=0xD9, unk=0x30 > [2.062716333333333] 0x0080, payload=[12 00 | ..], chk=0x6A < [2.111457750000000] 0x0004, flags=00, payload=[14 FF | ..], chk=0xE4, unk=0x32
Next some encrypted session is established. A 8 byte nonce is sent from Syscon (it appears random for each boot, cold or warm). Encrypted data from this point on always differs each boot.
> [2.111457750000000] 0x0010, payload=[ | ], chk=0xEE < [2.133389000000000] 0x0004, flags=80, payload=[ | ], chk=0x79, unk=0xFF > [2.133389000000000] 0x00A0, payload=[30 00 00 0B 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 | 0.......................................], chk=0xFB < [2.150567250000000] 0x0024, flags=00, payload=[ | ], chk=0xD9, unk=0xFF > [2.150567250000000] 0x0000, payload=[ | ], chk=0xFE < [2.155149500000000] 0x0024, flags=00, payload=[30 01 00 0B 00 00 00 00 A4 B0 EF 23 D6 9A 3A 06 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 | 0..........#..:.........................], chk=0x5F, unk=0x00 > [2.155149500000000] 0x00A0, payload=[30 00 00 0B 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 | 0.......................................], chk=0xFB < [2.163572000000000] 0x0004, flags=80, payload=[ | ], chk=0x79, unk=0x01 > [2.163572000000000] 0x00A0, payload=[30 02 00 0B 01 00 00 00 6C 7F E0 79 AA 03 4B B0 96 B7 42 F0 BC F8 62 7A 35 27 53 68 3D 0D ED A7 13 F2 32 77 46 2D 54 F8 | 0.......l..y..K...B...bz5'Sh=.....2wF-T.], chk=0x9B < [2.189271166666667] 0x0024, flags=00, payload=[ | ], chk=0xD9, unk=0x01 > [2.189271166666667] 0x0000, payload=[ | ], chk=0xFE < [2.193866583333334] 0x0024, flags=00, payload=[30 03 00 0B 00 00 00 00 7A 44 6E C8 F5 FA 35 CB 9B E9 E6 A0 B6 5C 85 1D FB A8 89 5C 9C 04 0B 29 34 59 55 EB 1D 98 AB 83 | 0.......zDn...5......\.....\...)4YU.....], chk=0xC6, unk=0x00 > [2.193866583333334] 0x00A0, payload=[30 02 00 0B 01 00 00 00 6C 7F E0 79 AA 03 4B B0 96 B7 42 F0 BC F8 62 7A 35 27 53 68 3D 0D ED A7 13 F2 32 77 46 2D 54 F8 | 0.......l..y..K...B...bz5'Sh=.....2wF-T.], chk=0x9B
Some more data is exchanged. Up until this point all the plaintext payloads appear to be the same from coldboot and warmboot.
< [2.202246333333334] 0x0004, flags=80, payload=[ | ], chk=0x79, unk=0x03 > [2.202246333333334] 0x088E, payload=[01 22 | ."], chk=0x43 < [2.206411750000000] 0x0004, flags=00, payload=[ | ], chk=0xF9, unk=0x03 > [2.206411750000000] 0x0000, payload=[ | ], chk=0xFE < [2.217062666666667] 0x0024, flags=00, payload=[ | ], chk=0xD9, unk=0x03 > [2.217062666666667] 0x0000, payload=[ | ], chk=0xFE < [2.221620916666667] 0x0024, flags=00, payload=[ | ], chk=0xD9, unk=0x03 > [2.221620916666667] 0x088E, payload=[01 22 | ."], chk=0x43 < [2.229805500000000] 0x0004, flags=80, payload=[ | ], chk=0x79, unk=0x03 > [2.229805500000000] 0x1082, payload=[80 04 08 | ...], chk=0xDD < [2.233887583333333] 0x0024, flags=00, payload=[ | ], chk=0xD9, unk=0x03 > [2.233887583333333] 0x0000, payload=[ | ], chk=0xFE < [2.238363416666667] 0x0024, flags=00, payload=[FF FF FF FF 01 FF FF FF | ........], chk=0xD7, unk=0x44 > [2.238363416666667] 0x1082, payload=[80 04 08 | ...], chk=0xDD < [2.246473916666667] 0x0004, flags=80, payload=[ | ], chk=0x79, unk=0xFF
Now, there appears to be a branch. The next sequence only shows up for cold boots.
> [2.246473916666667] 0x1082, payload=[A0 04 01 | ...], chk=0xC4
< [2.250555000000000] 0x0024, flags=00, payload=[ | ], chk=0xD9, unk=0xFF
> [2.250555000000000] 0x0000, payload=[ | ], chk=0xFE
< [2.255030833333334] 0x0024, flags=00, payload=[FF | .], chk=0xD9, unk=0x00
> [2.255030833333334] 0x1082, payload=[A0 04 01 | ...], chk=0xC4
< [2.259176583333333] 0x0004, flags=00, payload=[01 01 13 00 | ....], chk=0xE0, unk=0xFF
> [2.259176583333333] 0x1100, payload=[ | ], chk=0xED
< [2.263720583333333] 0x0004, flags=80, payload=[ | ], chk=0x79, unk=0x01
> [2.263720583333333] 0x00D0, payload=[30 00 00 0F 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 | 0.......................................], chk=0xC7
< [2.267827000000000] 0x0004, flags=00, payload=[ | ], chk=0xF9, unk=0x01
> [2.267827000000000] 0x0000, payload=[ | ], chk=0xFE
< [2.278339666666667] 0x0024, flags=00, payload=[ | ], chk=0xD9, unk=0x01
> [2.278339666666667] 0x0000, payload=[ | ], chk=0xFE
< [2.282830833333333] 0x0024, flags=00, payload=[30 01 00 0F 00 00 00 00 E1 CA 65 96 BB 7E 81 7A 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 | 0.........e..~.z........................], chk=0x97, unk=0x00
> [2.282830833333333] 0x00D0, payload=[30 00 00 0F 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 | 0.......................................], chk=0xC7
< [2.291023500000000] 0x0004, flags=80, payload=[ | ], chk=0x79, unk=0x01
> [2.291023500000000] 0x00D0, payload=[30 02 00 0F 01 00 00 00 4E D7 C0 7C D5 E8 BB D7 3E 9E 43 7B B2 E3 4D 81 23 C8 C4 BF B8 4D 9B 25 0A 3D C7 45 E6 0D 23 43 | 0.......N..|....>.C{..M.#....M.%.=.E..#C], chk=0x38
< [2.295129250000000] 0x0004, flags=00, payload=[ | ], chk=0xF9, unk=0x01
> [2.295129250000000] 0x0000, payload=[ | ], chk=0xFE
< [2.305641750000000] 0x0024, flags=00, payload=[ | ], chk=0xD9, unk=0x01
> [2.305641750000000] 0x0000, payload=[ | ], chk=0xFE
< [2.310132916666667] 0x0024, flags=00, payload=[30 03 00 0F 00 00 00 00 5B 3E 5C 5F 11 F9 E4 6A 85 0D 1E 06 9E F9 33 25 9B 95 55 21 39 48 FC 55 C7 BF A7 E4 32 AD FC 65 | 0.......[>\_...j......3%..U!9H.U....2..e], chk=0x55, unk=0x00
> [2.310132916666667] 0x00D0, payload=[30 02 00 0F 01 00 00 00 4E D7 C0 7C D5 E8 BB D7 3E 9E 43 7B B2 E3 4D 81 23 C8 C4 BF B8 4D 9B 25 0A 3D C7 45 E6 0D 23 43 | 0.......N..|....>.C{..M.#....M.%.=.E..#C], chk=0x38
< [2.318358166666667] 0x0004, flags=80, payload=[ | ], chk=0x79, unk=0x03
> [2.318358166666667] 0x00D0, payload=[30 04 00 0F 00 00 00 00 52 8D 6D BC 90 C9 00 EE FA CA 47 63 10 D1 4A E5 5A FD BB 91 3A 6C DA EF 64 CA 71 01 4A A9 D5 31 | 0.......R.m.......Gc..J.Z...:l..d.q.J..1], chk=0x4B
< [2.322464250000000] 0x0004, flags=00, payload=[ | ], chk=0xF9, unk=0x03
> [2.322464250000000] 0x0000, payload=[ | ], chk=0xFE
< [2.332976833333333] 0x0024, flags=00, payload=[ | ], chk=0xD9, unk=0x03
> [2.332976833333333] 0x0000, payload=[ | ], chk=0xFE
< [2.337468000000000] 0x0024, flags=00, payload=[30 05 00 0F 00 00 00 00 52 8D 6D BC 90 C9 00 EE FA CA 47 63 10 D1 4A E5 5A FD BB 91 3A 6C DA EF 64 CA 71 01 4A A9 D5 31 | 0.......R.m.......Gc..J.Z...:l..d.q.J..1], chk=0xF5, unk=0x00
> [2.337468000000000] 0x00D0, payload=[30 04 00 0F 00 00 00 00 52 8D 6D BC 90 C9 00 EE FA CA 47 63 10 D1 4A E5 5A FD BB 91 3A 6C DA EF 64 CA 71 01 4A A9 D5 31 | 0.......R.m.......Gc..J.Z...:l..d.q.J..1], chk=0x4B
< [2.345696333333333] 0x0004, flags=80, payload=[ | ], chk=0x79, unk=0x05
Then another set of shared sequence. Some differences in the warmboot responses though. On line 18,
FF BF FF 74
becomes
FF FF FF 74
. On line 12, the
00 00 00 00
becomes the address of the resume buffer (ex
F0 1E 1F 41
).
> [2.345696333333333] 0x00D2, payload=[20 7A 3E 7B 31 DE FC 3A 11 5F 64 E7 AB A4 EC 17 | .z>{1..:._d.....], chk=0x77
< [2.349790333333333] 0x0004, flags=00, payload=[ | ], chk=0xF9, unk=0x05
> [2.349790333333333] 0x0000, payload=[ | ], chk=0xFE
< [2.360448916666666] 0x0024, flags=00, payload=[ | ], chk=0xD9, unk=0x05
> [2.360448916666666] 0x0000, payload=[ | ], chk=0xFE
< [2.364930250000000] 0x0024, flags=00, payload=[9D 0B BC 4D BA 66 40 2C 63 BE F3 79 D0 31 26 1E 47 3A 64 DE 68 2F AE E2 8A B6 F0 27 37 46 89 16 0E 71 04 FA BF C9 4A A1 DF 4B EF D3 3D 0D 39 CD | ...M.f@,c..y.1&.G:d.h/.....'7F...q....J..K..=.9.], chk=0x11, unk=0x00
> [2.364930250000000] 0x00D2, payload=[20 7A 3E 7B 31 DE FC 3A 11 5F 64 E7 AB A4 EC 17 | .z>{1..:._d.....], chk=0x77
< [2.373236666666667] 0x0004, flags=80, payload=[ | ], chk=0x79, unk=0x0B
> [2.373236666666667] 0x0090, payload=[0C 00 04 | ...], chk=0x5B
< [2.377318583333333] 0x0024, flags=00, payload=[ | ], chk=0xD9, unk=0x0B
> [2.377318583333333] 0x0000, payload=[ | ], chk=0xFE
< [2.381794416666667] 0x0024, flags=00, payload=[00 00 00 00 | ....], chk=0xD5, unk=0x66
> [2.381794416666667] 0x0090, payload=[0C 00 04 | ...], chk=0x5B
< [2.385879750000000] 0x0004, flags=00, payload=[40 00 | @.], chk=0xB7, unk=0x00
> [2.385879750000000] 0x0800, payload=[ | ], chk=0xF6
< [2.386382583333333] 0x0004, flags=00, payload=[FF BF FF 74 | ...t], chk=0xC4, unk=0x66
> [2.386382583333333] 0x0100, payload=[ | ], chk=0xFD
< [2.386871833333333] 0x0004, flags=00, payload=[10 00 00 00 | ....], chk=0xE5, unk=0x66
> [2.386871833333333] 0x0003, payload=[ | ], chk=0xFB
< [2.387380083333333] 0x0000, flags=3F, payload=[ | ], chk=0xBE, unk=0x00
> [2.387380083333333] 0x0006, payload=[ | ], chk=0xF8
< [2.481997666666667] 0x0000, flags=80, payload=[ | ], chk=0x7D, unk=0x00
> [2.481986333333333] 0x00D2, payload=[30 14 F4 B8 84 89 81 AB 3D 07 66 DE AE B6 D3 24 | 0.......=.f....$], chk=0x10
< [2.514678500000000] 0x0020, flags=00, payload=[ | ], chk=0xDD, unk=0x00
> [2.514678500000000] 0x0000, payload=[ | ], chk=0xFE
< [2.519163916666667] 0x0020, flags=00, payload=[1A 1F BC 74 AA 16 59 D6 5C E7 FF 5B E0 85 B2 C8 39 2D D6 95 98 2F B7 4B 71 64 34 D7 8D 2C 94 A1 91 CB 73 D7 8D E1 D0 07 E6 1E 0F DA E7 51 BC 69 | ...t..Y.\..[....9-.../.Kqd4..,....s..........Q.i], chk=0x3C, unk=0x00
> [2.519163916666667] 0x00D2, payload=[30 14 F4 B8 84 89 81 AB 3D 07 66 DE AE B6 D3 24 | 0.......=.f....$], chk=0x10
< [2.527551416666667] 0x0000, flags=80, payload=[ | ], chk=0x7D, unk=0x1F
> [2.527540083333333] 0x088E, payload=[02 29 | .)], chk=0x3B
< [2.531619416666667] 0x0000, flags=00, payload=[ | ], chk=0xFD, unk=0x1F
> [2.531619416666667] 0x0000, payload=[ | ], chk=0xFE
< [2.542392416666666] 0x0020, flags=00, payload=[ | ], chk=0xDD, unk=0x1F
> [2.542392416666666] 0x0000, payload=[ | ], chk=0xFE
< [2.546867583333333] 0x0020, flags=00, payload=[ | ], chk=0xDD, unk=0x1F
> [2.546867583333333] 0x088E, payload=[02 29 | .)], chk=0x3B
Then, the two boot paths diverge completely (also note the time jump). It is suspected that at this point the kernel is started up on coldboot, and the kernel resumes for warmboot. For cold boot only, we see the beginning init sequence again, which is likely done in SceSyscon.
< [3.322105750000000] 0x0000, flags=00, payload=[0D 06 00 01 | ....], chk=0xE5, unk=0x16 > [3.322105750000000] 0x0001, payload=[ | ], chk=0xFD < [3.326563916666667] 0x0000, flags=00, payload=[32 30 31 32 31 31 30 38 31 37 30 34 | 201211081704], chk=0x96, unk=0x85 > [3.326552583333333] 0x0002, payload=[ | ], chk=0xFC < [3.331090666666667] 0x0000, flags=80, payload=[ | ], chk=0x7D, unk=0x30 > [3.331079333333333] 0x0080, payload=[12 00 | ..], chk=0x6A < [3.331576333333333] 0x0020, flags=00, payload=[ | ], chk=0xDD, unk=0x30 > [3.331576333333333] 0x0080, payload=[12 00 | ..], chk=0x6A < [3.332068833333333] 0x0000, flags=00, payload=[10 00 00 00 | ....], chk=0xE9, unk=0x31 > [3.332068833333333] 0x0004, payload=[ | ], chk=0xFA < [3.332541666666667] 0x0000, flags=00, payload=[00 FF 04 00 | ....], chk=0xF6, unk=0x31 > [3.332541666666667] 0x0103, payload=[ | ], chk=0xFA < [3.336980333333333] 0x0000, flags=00, payload=[10 00 00 00 | ....], chk=0xE9, unk=0x31 > [3.336980333333333] 0x0003, payload=[ | ], chk=0xFB ...