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 |
The following fields were intended to allow for custom panels. However, due to the way Linux now defines LCD panels, these fields were never actually used, and are not likely to ever be used. They are kept here for historical reasons.
| Size | Default Value | Description | Result if no EEPROM present |
|---|---|---|---|
| 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 (in version 2, indicates there is an IT6251) |
| 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 | EEPROM Oops support |
| 8 | 0x0100 | Root is on SATA (if 0, root is on internal MMC) |
| 9 | 0x0200 | Laptop is an "Heirloom" model |
| 10 | 0x0400 | Don't boot if lid is closed |
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) |
| 6 | 0x0040 | Auto-detect settings, rather than taking them from the EEPROM |
