ENUM VMBALLOON_CMD_TYPE(9)

📦 version 7.3.1, in nixpkgs unstable

💖 enum vmballoon_cmd_type(9) 💖

okay so bestie, welcome to the Kernel API Manual corner where we talk about enum vmballoon_cmd_type — literally the backdoor commands. it's giving “secret menu but make it kernel” and I'm obsessed. 🎀

✨ NAME ✨

enum vmballoon_cmd_type — backdoor commands.

✨ SYNOPSIS ✨

enum vmballoon_cmd_type {
    VMW_BALLOON_CMD_START ,
    VMW_BALLOON_CMD_GET_TARGET ,
    VMW_BALLOON_CMD_LOCK ,
    VMW_BALLOON_CMD_UNLOCK ,
    VMW_BALLOON_CMD_GUEST_ID ,
    VMW_BALLOON_CMD_BATCHED_LOCK ,
    VMW_BALLOON_CMD_BATCHED_UNLOCK ,
    VMW_BALLOON_CMD_BATCHED_2M_LOCK ,
    VMW_BALLOON_CMD_BATCHED_2M_UNLOCK ,
    VMW_BALLOON_CMD_VMCI_DOORBELL_SET ,
    VMW_BALLOON_CMD_LAST

};

🎀 Constants 🎀

okay here's the whole cast, no skips, no cap:

  • VMW_BALLOON_CMD_START — communicating supported version with the hypervisor. it's the “hi, what version are we on?” command 💬
  • VMW_BALLOON_CMD_GET_TARGET — gets the balloon target size. target acquired bestie 🎯
  • VMW_BALLOON_CMD_LOCK — informs the hypervisor about a ballooned page. locked in, literally 🔒
  • VMW_BALLOON_CMD_UNLOCK — informs the hypervisor about a page that is about to be deflated from the balloon. it's leaving the balloon era 🎈
  • VMW_BALLOON_CMD_GUEST_ID — informs the hypervisor about the type of OS that runs in the VM. guest identity reveal 🪪
  • VMW_BALLOON_CMD_BATCHED_LOCK — inform the hypervisor about a batch of ballooned pages (up to 512). batch processing, but cute 📦
  • VMW_BALLOON_CMD_BATCHED_UNLOCK — inform the hypervisor about a batch of pages that are about to be deflated from the balloon (up to 512). batch deflate moment 🎈
  • VMW_BALLOON_CMD_BATCHED_2M_LOCK — similar to VMW_BALLOON_CMD_BATCHED_LOCK for 2MB pages. 2MB page energy 🟦
  • VMW_BALLOON_CMD_BATCHED_2M_UNLOCK — similar to VMW_BALLOON_CMD_BATCHED_UNLOCK for 2MB pages. 2MB unlock slay 🟩
  • VMW_BALLOON_CMD_VMCI_DOORBELL_SET — a command to set doorbell notification that would be invoked when the balloon size changes. doorbell notification, but for balloon size changes 🔔
  • VMW_BALLOON_CMD_LAST — value of the last command. the final boss constant 👑

🌸 Description 🌸

okay so availability of the commands is as followed:

  • VMW_BALLOON_CMD_START, VMW_BALLOON_CMD_GET_TARGET and VMW_BALLOON_CMD_GUEST_ID are always available. always-on icons, periodt ✨
  • If the host reports VMW_BALLOON_BASIC_CMDS are supported then VMW_BALLOON_CMD_LOCK and VMW_BALLOON_CMD_UNLOCK commands are available. basic cmds check passed 💅
  • If the host reports VMW_BALLOON_BATCHED_CMDS are supported then VMW_BALLOON_CMD_BATCHED_LOCK and VMW_BALLOON_CMD_BATCHED_UNLOCK commands are available. batched cmds check passed 🦋
  • If the host reports VMW_BALLOON_BATCHED_2M_CMDS are supported then VMW_BALLOON_CMD_BATCHED_2M_LOCK and VMW_BALLOON_CMD_BATCHED_2M_UNLOCK are supported. 2M batched cmds check passed 🌈
  • If the host reports VMW_BALLOON_SIGNALLED_WAKEUP_CMD is supported then VMW_BALLOON_CMD_VMCI_DOORBELL_SET command is supported. signalled wakeup cmd check passed 🔔

🦋 SEE ALSO 🦋

okay the whole squad is linked here:

okay bye bestie 💖 — source/version: ./drivers/misc; date: October 2026; page: enum vmballoon_cmd_type(9) ✨

📦 where this page comes from