jules at penuchot.com
Mon Mar 15 13:33:24 GMT 2021
On 3/14/21 1:49 PM, vivek pandya wrote:
> Hi Jules,
> Nice to meet you!
Nice to meet you too :)
> I have been working on this experimental driver for sometime now.
> What I have been trying to do is inspired from
> https://github.com/baldurk/visor <https://github.com/baldurk/visor> , as
> I only work on this on weekends and I am not an expert in mesa codebase
> or SwiftShader I am referring to simple implementations like visor.
> As this is a software rasterizer it has a GPUStatus struct to hold
> indexBuffer and vertexBuffer , image is also stored as a pointer to
> bytes. Basically no hw abstraction in linux driver space to use actual
> memory on a device , everything is on CPU memory.
I'll look into it, thanks!
> The driver is able to execute a simple DrawTriangle function which
> executes vertex shader and fragment shader through LLVM's ORCJit but it
> does not generate meaningful results. Because codegeneration is not yet
> aware about the GPUStatus struct, that is the next thing I have to do to
> get the first triangle. Current code generation is all code copied from
> AMD's radv driver implementation which is not a software rasterizer.
> The resterization is a bit slower but it can be improved by threads but
> not a priority for now.
> However since the driver is able to receive the Draw command that means
> lots of vkCreate... functions are implemented to do basic stuff that is
> required to get up to this point.
> Also I am able to run
> that means driver is able to use image from a CPU memory and present it
> on display with mesa's WSI layers. And hopefully that means I am on the
> right path. Once I update codegen to use GPUStruct and get a triangle on
> screen it should be sufficient to prove that this is the correct way.
Sounds pretty nice already!
> The codebase is in C so it's a bit painful to work with. Also I have to
> use LLVM's C bindings to create IR an and that is very painful compared
> to LLVM's C++ API.
Could some parts of that codebase be turned into C++? I should be able
to help with that if you want.
> The code has lots of unused code as I started copying things from other
> implementations, I will clean up things but not a priority.
> An experienced mesa/vulkan driver engineer may not have taken this path
> but once I get a triangle on screen I will be more confident about my
> Hope this helps and if you dig into the codebase please feel free to
> send email to my email address (CC list) . I will be happy to explain.
I'll dig into it this week! I might not be as active as you during the
weekends however. I consider this work to be a good fit for my thesis so
I'll spend time on it during weekdays.
Awesome work so far.
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