This is intended to be a repository for info on the MStar/SigmaStar SoCs. The name is a parody of linux-sunxi for Allwinner SoCs. MStar in Chinese is chenxing and the newer SigmaStar name is xingchen.
This will probably never get as big as linux-sunxi so github pages should be more than enough.
Before MStar was bought out by MediaTek the company offered a wide range of SoCs focused at STB and camera applications. Since the company was bought by MediaTek the camera SoC part of the company has been spun out into the fully owned subsidiary called Sigmastar. The camera SoCs that are now marketed by Sigmastar will be the main focus here.
It’s worth noting that the MStar/Sigmastar camera SoCs seem to be derived from the SoCs made by Alpha Imaging Technology which was merged into MStar at some point.
|load u-boot SPL from vendor IPL||load u-boot from SPI NOR|
|boots to shell from initramfs||boots to shell from local storage||full system from local storage with network etc|
|sample device acquired||boot rom dumped||firmware dumped||SDK acquired||product brief acquired||datasheet acquired|
MStar used to make a lot of MIPS based SoCs for STBs. These aren’t that interesting in themselves but the IP blocks used in the MIPS SoCs were carried forward to the later ARM chips so any datasheets that can be found for the MIPS SoCs might help with reverse engineering the current ARM based ones.
To get the device tree out of the kernel you can use binwalk + extract-dtb and dtc.
binwalk -e <firmware.bin> extract-dtb.py <extracted firmware dir><uncompressed kernel blob> dtc -I dtb -O dts -o out.dts <extracted dtb that looks right>