Novena/EEPROM
Novena has a utility EEPROM that can be used for storing device-specific data. This is optional, and default values will be used if it is blank / not present.
All multi-byte integers are in native host order.
Version 1 structure
| Size | Default Value | Description | Result if no EEPROM present |
|---|---|---|---|
| 6 | 'Novena' | Unterminated EEPROM signature | The EEPROM contents will not be used |
| 1 | 1 | Version number of EEPROM structure | The EEPROM contents will not be used |
| 1 | 0 | Reserved | No change |
| 4 | 0 | Device serial number | No change |
| 6 | (Random) | Gigabit MAC address | Random MAC address is generated on each boot |
| 2 | 0 | Feature bitmask | No features are enabled |
Version 2 structure
The actual structure is defined in novena-eeprom.h as "struct novena_eeprom_data".
| Size | Default Value | Description | Result if no EEPROM present |
|---|---|---|---|
| 6 | 'Novena' | Unterminated EEPROM signature | The EEPROM contents will not be used |
| 1 | 2 | Version number of EEPROM structure | The EEPROM contents will not be used |
| 1 | 32 | Length of EEPROM read/write page | EEPROMOops may not be able to properly save panics |
| 4 | 0 | Device serial number | No change |
| 6 | (Random) | Gigabit MAC address | Random MAC address is generated on each boot |
| 2 | 0 | Feature bitmask | No features are enabled |
| 4 | 0 | LVDS channel 1 frequency | No display |
| 2 | 0 | LVDS channel 1 display width | No display |
| 2 | 0 | LVDS channel 1 display height | No display |
| 2 | 0 | LVDS channel 1 horizontal back porch | No display |
| 2 | 0 | LVDS channel 1 horizontal front porch | No display |
| 2 | 0 | LVDS channel 1 horizontal sync length | No display |
| 2 | 0 | LVDS channel 1 vertical back porch | No display |
| 2 | 0 | LVDS channel 1 vertical front porch | No display |
| 2 | 0 | LVDS channel 1 vertical sync length | No display |
| 4 | 0 | LVDS channel 1 flags (see below) | No display |
| 4 | 0 | LVDS channel 2 frequency | No display |
| 2 | 0 | LVDS channel 2 display width | No display |
| 2 | 0 | LVDS channel 2 display height | No display |
| 2 | 0 | LVDS channel 2 horizontal back porch | No display |
| 2 | 0 | LVDS channel 2 horizontal front porch | No display |
| 2 | 0 | LVDS channel 2 horizontal sync length | No display |
| 2 | 0 | LVDS channel 2 vertical back porch | No display |
| 2 | 0 | LVDS channel 2 vertical front porch | No display |
| 2 | 0 | LVDS channel 2 vertical sync length | No display |
| 4 | 0 | LVDS channel 2 flags (see below) | No display |
| 4 | 0 | HDMI default frequency | No display |
| 2 | 0 | HDMI default display width | No display |
| 2 | 0 | HDMI default display height | No display |
| 2 | 0 | HDMI default horizontal back porch | No display |
| 2 | 0 | HDMI default horizontal front porch | No display |
| 2 | 0 | HDMI default horizontal sync length | No display |
| 2 | 0 | HDMI default vertical back porch | No display |
| 2 | 0 | HDMI default vertical front porch | No display |
| 2 | 0 | HDMI default vertical sync length | No display |
| 4 | 0 | HDMI default flags (see below) | No display |
| 4 | 4096 | EEPROM capacity (in bytes) | No change |
| 4 | 4096 | EEPROMoops offset (in bytes) | EEPROMoops support will be disabled |
| 4 | 61440 | EEPROMoops length (in bytes) | EEPROMoops support will be disabled |
Feature bitmask
There is a bitmask field that defines various board features. In this way, a single image can be shipped that supports various components. For example, a router might not have a display, but a laptop would need to have its LCD turned on. A bit is "1" if the feature is present (and needs to be enabled), and "0" if it is not present. Note that some values are mutually-exclusive (e.g. you can only have one kind of LVDS display attached).
| Bit position | Mask | Feature |
|---|---|---|
| 0 | 0x0001 | ES8328 Audio Codec |
| 1 | 0x0002 | Senono-based battery board |
| 2 | 0x0004 | Retina LVDS display (flag ignored in version 2) |
| 3 | 0x0008 | (Reserved: Other LVDS display) |
| 4 | 0x0010 | mPCIe port |
| 5 | 0x0020 | Gigabit Ethernet |
| 6 | 0x0040 | HDMI Output (flag ignored in version 2) |
| 7 | 0x0080 | Root is on SATA (if 0, root is on internal MMC) |
LVDS/HDMI flags bitmask
| Bit position | Mask | Feature |
|---|---|---|
| 0 | 0x0001 | Channel is present |
| 1 | 0x0002 | If 1, use both LVDS channels together |
| 2 | 0x0004 | Polarity of vsync signal |
| 3 | 0x0008 | Polarity of hsync signal |
| 4 | 0x0010 | 1 if LVDS is JEIDA mapping, 0 if it's PSWG/SWPG |
| 5 | 0x0020 | 1 if data is 8-bit (24 bpp), 0 if it's 6-bit (18 bpp) |
