drm_gem_fb_begin_cpu_access(9)

🎀 drm_gem_fb_begin_cpu_access — the "hey bestie, wake up the buffers" call 🎀

okay so real quick, this is the drm_gem_fb_begin_cpu_access(9) page from the Kernel API Manual, and honestly? it's a short one but it's important, so pay attention 💅

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✨ NAME ✨

drm_gem_fb_begin_cpu_access — gets your GEM buffer objects all dressed and ready for CPU access 🫶

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🌸 SYNOPSIS 🌸

int drm_gem_fb_begin_cpu_access (struct drm_framebuffer *fb , enum
       dma_data_direction dir );

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💖 ARGUMENTS 💖

• fb — the framebuffer. yes. that one. the framebuffer 🦋
• dir — the access mode, i.e. which direction we're going. iconic of it honestly.

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🧚 DESCRIPTION 🧚

So here's the vibe check: this function preps a framebuffer's GEM buffer objects for CPU access. You literally have to call it before you go touching the BO data inside the kernel — like, no cap, it's a requirement, not a suggestion 🔥

And the way that imported BOs get special treatment?? Obsessed. For imported BOs, the function calls dma_buf_begin_cpu_access. slay.

💀 also!! when you're done, you gotta signal the end of CPU access — see drm_gem_fb_end_cpu_access for that. don't just leave it hanging bestie 😭

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⭐ RETURN ⭐

0 on success, or a negative errno code otherwise. that's it. that's the whole return section. short king 👑

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🌈 SEE ALSO 🌈

• Kernel file ./drivers/gpu/drm/drm_gem_framebuffer_helper.c overview(9)
• drm_gem_fb_get_obj(9)
• drm_gem_fb_destroy(9)
• drm_gem_fb_create_handle(9)
• drm_gem_fb_init_with_funcs(9)
• drm_gem_fb_create_with_funcs(9)
• drm_gem_fb_create(9)
• drm_gem_fb_create_with_dirty(9)
• drm_gem_fb_vmap(9)
• drm_gem_fb_vunmap(9)
• drm_gem_fb_end_cpu_access(9)
• drm_gem_fb_afbc_init(9)

like, go read all of them. it's giving study group 📚✨

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and that's the whole page!! tysm for reading, mwah 💋 this little gem lives in ./drivers/gpu/drm, dated October 2026, and it's part of the Kernel API Manual — so when you cite it, you cite it correctly. periodt 🎀🦋💜