One of the major downsides of the Hexagon DSP is that its near impossible to actually run anything on it unless you somehow get your hands on an unprovisioned/unlocked SoC.
The HLOS (High-level OS) running on the Hexagon requires every "applet" to be signed by either the Qualcomm root cert or the OEMs cert. Usually, every phone has a set of generic Hexagon applets (or "skeleton libs") that are provided and signed by the OEM, which seem to be freely usable to offload some computational work to the DSP (mainly FastCV et al - https://developer.qualcomm.com/sites/default/files/docs/qual...).
Those of course come with their own bugs: https://research.checkpoint.com/2021/pwn2own-qualcomm-dsp/
On some older SoCs, you were able to use a TOCTOU (Time of check to time of use) exploit to bypass the signature check by patching the applet loader shim in-memory, once it itself got authenticated: https://github.com/geohot/freethedsp/ (I have personally ported this to the msm8953, and it seems to work)
The HLOS (High-level OS) running on the Hexagon requires every "applet" to be signed by either the Qualcomm root cert or the OEMs cert. Usually, every phone has a set of generic Hexagon applets (or "skeleton libs") that are provided and signed by the OEM, which seem to be freely usable to offload some computational work to the DSP (mainly FastCV et al - https://developer.qualcomm.com/sites/default/files/docs/qual...). Those of course come with their own bugs: https://research.checkpoint.com/2021/pwn2own-qualcomm-dsp/
On some older SoCs, you were able to use a TOCTOU (Time of check to time of use) exploit to bypass the signature check by patching the applet loader shim in-memory, once it itself got authenticated: https://github.com/geohot/freethedsp/ (I have personally ported this to the msm8953, and it seems to work)