SysCfg

"SysCfg" is the system configuration sector of an iPod. It carries unique per-device information such as the serial number, as well as determining which region a device was sold in, the model number, etc. On the iPod nano 3rd generation and the iPod Classic, it is stored in the first section of the NOR.

WARNING: Messing with SysCfg can result in a device that can not be restored in iTunes, and may not boot! You MUST keep backups!

Structure

The header of the SysCfg always begins with a 'SCfg' tag in a 24 byte header. Some of the header values are unknown.

struct SysCfgHeader {
  uint32_t magic; // always 'SCfg'
  uint32_t size;
  uint32_t unknown1; // 0x00000200 on iPod classic
  uint32_t version; // maybe? 0x00010001 on iPod classic
  uint32_t unknown2; // 0x00000000 on iPod classic
  uint32_t num_entries;
}; // 0x18

Each entry in the SysCfg consists of a 32-bit tag value (in little-endian) and up to 16 (0x10) bytes of data. The way the data is encoded is dependent on the tag value.

struct SysCfgEntry {
  uint32_t tag;
  uint8_t data[0x10];
};

Tags

Tag	Meaning	Data type
SrNm	Serial Number	ASCII characters
Mod#	Model Number	ASCII characters
FwId	Firmware ID	Unknown
HwId	Hardware ID	Unknown
Regn	Sales Region	Unknown
HwVr	Hardware Version	4 16-bit shorts
SwVr	Software Version - that the device shipped with?	ASCII characters
MLBN	Logic Board Serial Number	ASCII characters
Codc	Unknown	Unknown

Example Values

iPod classic (6th generation), 80GB, Black

Tag	Value	Notes
SrNm	8K823xxxYMV	Redacted device identifier
Mod#	MB147
FwId	0x01000000 0x13622A6C 0x000A2700	Interpreted as 3 32-bit LE integers
HwId	0x82021685	Interpreted as 1 32-bit LE integer
Regn	0x0001 0x0002 0x0025 0x0001	Sold in UK. Interpreted as 4 16-bit LE shorts
HwVr	0x0013.0x0000.0x0000.0x0000	Reversed order
SwVr	1.0
MLBN	BR8604P11007
Codc	SB	Interpreted as ASCII characters

iTunes restores this device to firmware 1.1.2

Behaviours

• WTF for 0x1223 / S5L8702 devices uses HwVr to determine which USB PID to use.

References

• SysCfg on The Apple Wiki