sdma_v4_0_emit_copy_buffer(9)

📦 version 7.3.1, in nixpkgs unstable

💅 sdma_v4_0_emit_copy_buffer — kernel API manual, bestie edition ✨

okay so real talk, this is a page from the Kernel API Manual and it's genuinely iconic: sdma_v4_0_emit_copy_buffer — literally the function that copies buffers using the sDMA engine. no cap. let's get into it 🫶

🌸 NAME 🌸

sdma_v4_0_emit_copy_buffer — copy buffer using the sDMA engine 💖

✨ SYNOPSIS ✨

void sdma_v4_0_emit_copy_buffer (struct amdgpu_ib *ib , uint64_t
src_offset , uint64_t dst_offset , uint32_t byte_count , uint32_t
copy_flags );

like, that's the whole signature. void return, five args, we move. 🎀

🦋 ARGUMENTS 🦋

okay so every single one of these matters, don't skip:

  • ib — the indirect buffer to copy to. that's the destination of the command, bestie, not the data. iykyk 💅
  • src_offset — src GPU address 🌟
  • dst_offset — dst GPU address 🌟
  • byte_count — number of bytes to xfer. yes, xfer. that's the word. we respect the word. 💀
  • copy_flags — copy flags for the buffers 🚩

🔥 DESCRIPTION 🔥

so what does it actually do? it copies GPU buffers using the DMA engine, specifically for VEGA10/12. main character energy fr fr 👑

and who's out here calling it? the amdgpu ttm implementation uses it to move pages — but only if it's registered as the asic copy callback. that conditional is doing a lot of work, don't sleep on it 🙈

🌈 SEE ALSO 🌈

the whole friend group, in order, no one left out:

and that's the page!! 🧚 this lil beauty lives in ./drivers/gpu/drm/amd/amdgpu, dated October 2026, and the whole thing is sdma_v4_0_emit_copy_buffer(9) — go forth and emit those copy buffers, bestie 💜✨

📦 where this page comes from