vmw_bo_cpu_blit(9)

✨ vmw_bo_cpu_blit(9) — kernel API manual, bestie edition ✨

okay so this is a page straight out of the Kernel API Manual and honestly? it's giving "niche but iconic." we're talking about vmw_bo_cpu_blit(9), and yes, the (9) means it's a kernel thing, so put your serious hat on (but keep the sparkle) 💅

---

🌸 NAME 🌸

vmw_bo_cpu_blit — an in-kernel cpu blit. that's it, that's the whole vibe. it copies stuff from one buffer object to another, but doing it with the cpu, no cap 🫶

---

🦋 SYNOPSIS 🦋

int vmw_bo_cpu_blit (struct vmw_bo *vmw_dst , u32 dst_offset , u32
       dst_stride , struct vmw_bo *vmw_src , u32 src_offset , u32 src_stride ,
       u32 w , u32 h , struct vmw_diff_cpy *diff );

like, nine arguments, bestie. she's high maintenance but she's worth it ✨

---

💜 ARGUMENTS 💜

• vmw_dst — the destination buffer object. where the pixels are going 💫
• dst_offset — destination offset where the blit starts, measured in bytes.
• dst_stride — destination stride, also in bytes. (yes, bytes again. keep up 🎀)
• vmw_src — the source buffer object. where the pixels are coming from.
• src_offset — source offset where the blit starts, in bytes.
• src_stride — source stride, in bytes. consistent queen.
• w — width of the blit. 📏
• h — height of the blit. 📐
• diff — the struct vmw_diff_cpy used to track the modified bounding box. she's keeping receipts on exactly what changed 👑

---

🎀 RETURN 🎀

• Zero on success. slay ✅
• Negative error value on failure. sad but valid 😭
• will print out kernel warnings on caller bugs. so if you messed up, the kernel will be loud about it, fr fr 💀

---

🔥 DESCRIPTION 🔥

so what does she actually do? performs a CPU blit from one buffer object to another, avoiding a full bo vmap — because that vmap can literally exhaust or fragment vmalloc space, and we are not about that life 🙈

on supported architectures (x86), we're using kmap_atomic, which avoids cross-processor TLB- and cache flushes, and may — on non-HIGHMEM systems — reference already set-up mappings. efficiency icon behavior, honestly ⚡

⚠️ big warning, bestie, read this twice: neither of the buffer objects may be placed in PCI memory (Fixed memory in TTM terminology) when using this function. like, just don't. it's not a vibe. 🚫

---

🧚 SEE ALSO 🧚

kernel file ./drivers/gpu/drm/vmwgfx/vmwgfx_blit.c — the source of truth ✨

then the whole friend group:

• vmw_find_first_diff(9)
• vmw_find_last_diff(9)
• vmw_memcpy(9)
• vmw_adjust_rect(9)
• vmw_diff_memcpy(9)
• struct vmw_bo_blit_line_data(9)
• vmw_bo_cpu_blit_line(9)

---

and that's the page, bestie 💖 this cutie lives over at ./drivers/gpu/drm/vmwgfx, dated October 2026 — go off, vmwgfx, periodt. 🌈👑