When I tried to bring NVMe support on my M3 device, I found that there're references to ans3. I thought that this new coprocessor is M3 specific and is different from the previous ans2, which is why NVMe driver for my M3 was crashing in both m1n1 and linux. But I was pointed out that if you would use an M3 device on previous firmware versions, the same code used for ans2 would work no problem. And with newer version the older M1/M2 NVMe coprocessors also stopped working.
Thus, it is probable that the update for ans in this document would work on that devices too, but I cannot tell for sure since I only have an M3 device. So this is bound for checking.
The only key differences I could spot are the register offsets. They're all different for the new ans3.
Here're all the register differences comparing to previous values:
| Register | Previous addresses | New addresses working with M3/ans3 |
|---|---|---|
| unknown_ctrl | 0x24008 | 0x28130 |
| linear_sq_ctrl | 0x24908 | 0x2813c |
| db_linear_asq | 0x2490c | 0x2490c |
| db_linear_iosq | 0x24910 | 0x24910 |
Also, I don't know if it is me doing something wrong, or the new ans is stricter with memory. I needed to allow 1TB address space in m1n1 for the new ans to properly initialize, otherwise it would crash.
sart_add_allowed_region(nvme_sart, (void *)0, 0x10000000000UL);I am sure that's just wrong and needs to be done differently, so again it is bound for proper revision.
One last thing: in the m1n1 drive i updated the cmd.cdw12 value in the nvme_read function. The cmd.cdw12 now should contain 0 instead of 1. Without it the read commands were failing on my side. Found it on pure accident and also not sure whether it is necessary.