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Simultaneous read access on DMA #89

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Hitz337 opened this issue Jun 25, 2024 · 0 comments
Open

Simultaneous read access on DMA #89

Hitz337 opened this issue Jun 25, 2024 · 0 comments

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@Hitz337
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Hitz337 commented Jun 25, 2024

CocoTB: 1.8.1
CocoTBext_AXI: 0.1.24
Simulator: ModelSim DE Plus
System: Ubuntu 22.04 LTS

Hello,

I have seen an issue when using the address abstraction feature. Here's the context:
I have an address space of size 2*32. I registered 3 regions with a sparse memory object of size 2**28 and created 3 windows with 0x00000000, 0x10000000 and 0x20000000 offsets respectively.
The whole space is available to 4 AXI IF for write only. 3 other read-only AXI IF can access the specific windows respectively.

The issue is:
I forked 2 write coroutines, one which writes to 1st window and the 2nd writes to the second window. I also have 2 read coroutines which read from 1st and 2nd windows concurrently. The read operation occurs after all the data has been written.
When reading concurrently, the values from the 1st and 2nd coroutine correspond to the values written in the 2nd window. I access the values written in the 2nd window when reading the 1st window even though the read address is correct.
Is there and issue when accessing simultaneously 2 different addresses of the same address space?

Thanks for your help!

p.s.
cocotb_read_cache drawio

@Hitz337 Hitz337 changed the title Simultaneous read access on AXI interface Simultaneous read access on DMA Jun 25, 2024
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