In order to run free software bootloaders, we need the ability to run the code we want at boot.
However in most smartphones and many tablets use code signature at boot, which prevent us to run free software bootloader.
In practice:| Device and documentation | Freedom situation | Boot order |
|---|---|---|
| Samsung Nexus S (i902x) | Proprietary, Signed on the tested devices | ?->USB->?->eMMC->? |
| Samsung Galaxy S2 (i9100) | Proprietary, probably Signed | ? |
| Samsung Galaxy Tab 2 | Proprietary, signed | ?->USB->?->eMMC->? |
| LG Optimus black (p970) | unsigned, can be replaced with upstream u-boot | eMMC(MMC2)->USB |
| Galaxy SIII (I9300) Galaxy SIII 4G (I9305) Galaxy Note II (N7100) Galaxy Note II 4G (N7105) |
* Proprietary, Signed * There is work in progress to understand if we can avoid the signature |
?->eMMC->?->USB->? |
| Golden Delicous GTA04 | unsigned, free software | * Aux not pressed during boot: ? * Aux pressed during boot: ?->SD->?->NAND SYS_BOOT0 = 1 SYS_BOOT1 = 1 SYS_BOOT2 = 1 SYS_BOOT3 = 1 SYS_BOOT4 = 1 SYS_BOOT5 = AUX button SYS_BOOT6 = 1 But cannot find Reference manual for the DM370 |
| SOC and documentation | Freedom situation |
|---|---|
| Exynos 4 | * Some or all devices are signed * work in progress to understand if it's possible to bypass the signature |
| BroadcomVideoCore | The SOCs have the ability to check signatures |
| TegraBootrom | * Not all devices use code signature * Boot from USB is possible thanks to fusee_gelee * Code can be appended to the bootrom by writing in a fuse area. Could that be used to disable code signature ? |
| IMX 5 and 6 | * Not all devices are signed * Thanks to Ref_QBVR2017-0001.txt it's possible to bypass signatures anyway, and maybe load code through USB too |