STRUCT DRM_PANTHOR_VM_CREATE(9)

💅 struct drm_panthor_vm_create(9) 🎀

okay so bestie, this is a page from the Kernel API Manual and it's literally all about struct drm_panthor_vm_create — the little args package you hand over to DRM_PANTHOR_IOCTL_VM_CREATE when you want a shiny new VM. no cap, that's the whole vibe. 💖

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✨ NAME ✨

struct drm_panthor_vm_create — the arguments you pass in to DRM_PANTHOR_IOCTL_VM_CREATE 🫶

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🌸 SYNOPSIS 🌸

struct drm_panthor_vm_create {
    __u32 flags;
    __u32 id;
    __u64 user_va_range;
 };

look at her. three fields. immaculate. 👑

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🦋 Members 🦋

okay let's meet the cast, one by one, they all ate:

• flags — the VM flags. MBZ, and if you don't know what MBZ means, it stands for Must Be Zero — so like… don't touch, bestie. leave it at zero, it's giving ✨respect the protocol✨.
• id — this one's a returned VM ID. so the kernel fills it in for you, you don't write it. it's the kernel's little gift back 🎁.
• user_va_range — the size of the VA space that's reserved for user objects. this is the main character of the struct, fr fr.

okay so this next bit is important, listen up 💀

the kernel is gonna pick the remaining space to map kernel-only objects into the VM — and by that I mean heap chunks, heap context, ring buffers, kernel synchronization objects, ... the whole squad. 😭 so if the space left over for kernel objects is too small, kernel object allocation will fail further down the road. like, not now. later. sneak attack. 💀

one can use drm_panthor_gpu_info::mmu_features to extract the total virtual address range, and then chose a user_va_range that leaves some space to the kernel. (yes, that's "chose" — the original says "chose" — we don't gatekeep, we just quote 🫶)

if user_va_range is zero, the kernel will pick a sensible value based on TASK_SIZE and the virtual range supported by the GPU MMU. and like, the reasoning is kind of iconic: the kernel/user split should leave enough VA space for userspace processes to support SVM, while still allowing the kernel to map some amount of kernel objects in the kernel VA range. ✨ the value chosen by the driver will be returned in user_va_range — so you get to see what it decided, slay 🙈

and for the layout girlies: user VA space always starts at 0x0, and kernel VA space is always placed after the user VA range. periodt. 💅

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🌈 SEE ALSO 🌈

literally so many friends, buckle up bestie, this is the whole group chat:

• Kernel file ./include/uapi/drm/panthor_drm.h
• Introduction(9)
• MMIO regions exposed to userspace.(9)
• IOCTL IDs(9)
• IOCTL arguments(9)
• struct drm_panthor_obj_array(9)
• DRM_PANTHOR_OBJ_ARRAY(9)
• enum drm_panthor_sync_op_flags(9)
• struct drm_panthor_sync_op(9)
• enum drm_panthor_dev_query_type(9)
• enum drm_panthor_gpu_coherency(9)
• struct drm_panthor_gpu_info(9)
• struct drm_panthor_csif_info(9)
• enum drm_panthor_timestamp_info_flags(9)
• struct drm_panthor_timestamp_info(9)
• struct drm_panthor_mmu_info(9)
• struct drm_panthor_group_priorities_info(9)
• struct drm_panthor_dev_query(9)
• struct drm_panthor_vm_destroy(9)
• enum drm_panthor_vm_bind_op_flags(9)
• struct drm_panthor_vm_bind_op(9)
• enum drm_panthor_vm_bind_flags(9)
• struct drm_panthor_vm_bind(9)
• enum drm_panthor_vm_state(9)
• struct drm_panthor_vm_get_state(9)
• enum drm_panthor_bo_flags(9)
• struct drm_panthor_bo_create(9)
• struct drm_panthor_bo_mmap_offset(9)
• struct drm_panthor_queue_create(9)
• enum drm_panthor_group_priority(9)
• struct drm_panthor_group_create(9)
• struct drm_panthor_group_destroy(9)
• struct drm_panthor_queue_submit(9)
• struct drm_panthor_group_submit(9)
• enum drm_panthor_group_state_flags(9)
• struct drm_panthor_group_get_state(9)
• struct drm_panthor_tiler_heap_create(9)
• struct drm_panthor_tiler_heap_destroy(9)
• struct drm_panthor_bo_set_label(9)
• struct drm_panthor_set_user_mmio_offset(9)
• enum drm_panthor_bo_sync_op_type(9)
• struct drm_panthor_bo_sync_op(9)
• struct drm_panthor_bo_sync(9)
• enum drm_panthor_bo_extra_flags(9)
• struct drm_panthor_bo_query_info(9)
• DRM_IOCTL_PANTHOR(9)

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and that's the page, bestie!! 🧚💜 this little drop came from ./include/uapi/drm and it's dated October 2026 — go forth and create VMs responsibly, ily, bye!! 🌸🎀💖