Hi,
We're working on a user space debugger for AMDGPU devices and are trying
to figure out a "proper" way of taking mapped pages and converting them
back to physical addresses so the debugger can read memory that was sent
to the GPU.
The debugger largely operates at arms length from the application being
debugged so it has no knowledge of the buffers other than which PCI
device mapped it and the mapped address.
We also use the debugger to read back kernel programmed buffers (ring
buffers and the like) so we really need a kernel level solution.
As a prototype I put a trace point in the AMDGPU driver when
pci_map_page() is called which preserves the physical and dma address
and that works but obviously is a bit of a hack and doesn't work if
pages are mapped before the trace is enabled.
Ideally, some form of debugfs interface would be nice.
Is there any sort of interface already I can take advantage of? I've
tried enabling the map/unmap tracepoints before loading amdgpu and it
produced no traffic in the trace file.
Thanks,
Tom
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