View source for 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 ==

{| class="wikitable"
|-
! Tag !! Meaning !! Data type
|-
| SrNm || Serial Number || ASCII characters
|-
| Mdo# || 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 ====

{| class="wikitable"
|-
! Tag !! Value !! Notes
|-
| SrNm || 8K823xxxYMV || Redacted device identifier
|-
| Mdo# || 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 ==

* [https://theapplewiki.com/wiki/SysCfg SysCfg on The Apple Wiki]