Hi, first time here and first time working on any sort of Kernel driver, so I hope I'm doing things right by asking my question through this list.

I have managed to get audio working for the Creative Sound Blaster Z by reverse engineering the driver and firmware from Windows. I created a program to capture the HDA verbs as they happen in Windows through QEMU using vfio pci passthrough.

Now, here's where I'm kind of stumped. I created a program to send the commands that route the audio to it's output on the card. If I run these commands after the driver has already loaded in Linux, it works fine and I get audio. However, if I run these commands inside of the driver, there is no audio.

There is an 8051 cpu onboard, and I can dump the contents of its memory through HDA-verbs. I compared dumps of the 8051 while audio is working with the script to dumps when the audio is broken from putting the commands inside of the driver. Just about everything is the same, except for a region I have figured out has to do with the streams. Each audio stream seems to have an ID, and for some reason, if the commands are run inside of the driver, it seems like the stream ID's get messed with.

My current theory is that the streams are assigned in order of streams started. So, after my command to start audio, it expects the next stream to be the output audio stream. It also seems like compared to Windows, a lot more stream commands are used. Maybe extra streams are being initiated that are unused, and are interfering with the card.

So, my question is, how would I go about starting a stream, maybe like a dummy stream, so it is assigned properly? Are there any examples of this? If someone could point me to where streams are even initiated it would be helpful.

My next question is the legality of distributing the firmware. I was able to pull the Sound Blaster Z's firmware from the Windows driver file. Since that is a publicly available file, is it legal to redistribute? I have no experience with this kind of thing. Maybe someone here has someone within Creative I could ask or something.

Anyways, like I said, this is my first time doing anything like this. Please correct me if I've done anything wrong, and let me know if anyone needs to see my current driver.

Thanks, Connor M.