# Memory Layout ## x86-64 guest physical memory map This is a survey of the existing memory layout for crosvm on x86-64 when booting a Linux kernel. Some of these values are different when booting a BIOS image or when compiled with features=direct (ManaTEE); see the source. All addresses are in hexadecimal. | Name/source link | Address | End (exclusive) | Size | Notes | | ---------------------------- | ------------- | --------------- | --------- | ---------------------------------------------------------------------------------------- | | | `0000` | `7000` | | RAM (may start at 0x1000 for crosvm-direct) | | [`ZERO_PAGE_OFFSET`] | `7000` | | | Linux boot_params structure | | [`BOOT_STACK_POINTER`] | `8000` | | | Boot SP value | | [`boot_pml4_addr`] | `9000` | | | Boot page table | | [`boot_pdpte_addr`] | `A000` | | | Boot page table | | [`boot_pde_addr`] | `B000` | | | Boot page table | | [`CMDLINE_OFFSET`] | `2_0000` | `2_0800` | 2 KiB | Linux kernel command line | | [`SETUP_DATA_START`] | `2_0800` | `E_0000` | 766 KiB | Linux kernel `setup_data` linked list | | [`ACPI_HI_RSDP_WINDOW_BASE`] | `E_0000` | | | ACPI tables | | [`KERNEL_START_OFFSET`] | `20_0000` | | | Linux kernel image load address | | [`initrd_start`] | after kernel | | | Initial RAM disk for Linux kernel (optional) | | [`END_ADDR_BEFORE_32BITS`] | after initrd | `D000_0000` | ~3.24 GiB | RAM (\<4G) | | [`END_ADDR_BEFORE_32BITS`] | `D000_0000` | `F400_0000` | 576 MiB | Low (\<4G) MMIO allocation area | | [`PCIE_CFG_MMIO_START`] | `F400_0000` | `F800_0000` | 64 MiB | PCIe enhanced config (ECAM) | | [`RESERVED_MEM_SIZE`] | `F800_0000` | `1_0000_0000` | 128 MiB | LAPIC/IOAPIC/HPET/… | | [`TSS_ADDR`] | `FFFB_D000` | | | Boot task state segment | | | `1_0000_0000` | | | RAM (>4G) | | | (end of RAM) | | | High (>4G) MMIO allocation area | [`zero_page_offset`]: https://crsrc.org/o/src/platform/crosvm/x86_64/src/lib.rs;l=338?q=ZERO_PAGE_OFFSET [`boot_stack_pointer`]: https://crsrc.org/o/src/platform/crosvm/x86_64/src/lib.rs;l=332?q=BOOT_STACK_POINTER [`boot_pml4_addr`]: https://crsrc.org/o/src/platform/crosvm/x86_64/src/regs.rs;l=299?q=boot_pml4_addr [`boot_pdpte_addr`]: https://crsrc.org/o/src/platform/crosvm/x86_64/src/regs.rs;l=300?q=boot_pdpte_addr [`boot_pde_addr`]: https://crsrc.org/o/src/platform/crosvm/x86_64/src/regs.rs;l=301?q=boot_pde_addr [`cmdline_offset`]: https://crsrc.org/o/src/platform/crosvm/x86_64/src/lib.rs;l=342?q=CMDLINE_OFFSET [`setup_data_start`]: https://crsrc.org/o/src/platform/crosvm/x86_64/src/lib.rs;l=344?q=SETUP_DATA_START [`acpi_hi_rsdp_window_base`]: https://crsrc.org/o/src/platform/crosvm/x86_64/src/lib.rs;l=357?q=ACPI_HI_RSDP_WINDOW_BASE [`kernel_start_offset`]: https://crsrc.org/o/src/platform/crosvm/x86_64/src/lib.rs;l=341?q=KERNEL_START_OFFSET [`initrd_start`]: https://crsrc.org/o/src/platform/crosvm/x86_64/src/lib.rs;l=1633?q=initrd_start [`end_addr_before_32bits`]: https://crsrc.org/o/src/platform/crosvm/x86_64/src/lib.rs;l=230?q=END_ADDR_BEFORE_32BITS [`pcie_cfg_mmio_start`]: https://crsrc.org/o/src/platform/crosvm/x86_64/src/lib.rs;l=400?q=PCIE_CFG_MMIO_START [`reserved_mem_size`]: https://crsrc.org/o/src/platform/crosvm/x86_64/src/lib.rs;l=395?q=RESERVED_MEM_SIZE [`tss_addr`]: https://crsrc.org/o/src/platform/crosvm/x86_64/src/lib.rs;l=339?q=TSS_ADDR ## aarch64 guest physical memory map All addresses are IPA in hexadecimal. ### Common layout These apply for all boot modes. | Name/source link | Address | End (exclusive) | Size | Notes | | --------------------------------- | --------------- | --------------- | ---------- | ------------------------------------------------------------- | | [`SERIAL_ADDR[3]`][serial_addr] | `2e8` | `2f0` | 8 bytes | Serial port MMIO | | [`SERIAL_ADDR[1]`][serial_addr] | `2f8` | `300` | 8 bytes | Serial port MMIO | | [`SERIAL_ADDR[2]`][serial_addr] | `3e8` | `3f0` | 8 bytes | Serial port MMIO | | [`SERIAL_ADDR[0]`][serial_addr] | `3f8` | `400` | 8 bytes | Serial port MMIO | | [`AARCH64_RTC_ADDR`] | `2000` | `3000` | 4 KiB | Real-time clock | | [`AARCH64_VMWDT_ADDR`] | `3000` | `4000` | 4 KiB | Watchdog device | | [`AARCH64_PCI_CFG_BASE`] | `1_0000` | `2_0000` | 64 KiB | PCI configuration (CAM) | | [`AARCH64_PVTIME_IPA_START`] | `1f0_0000` | `200_0000` | 64 KiB | Paravirtualized time | | [`AARCH64_MMIO_BASE`] | `200_0000` | `400_0000` | 32 MiB | Low MMIO allocation area | | [`AARCH64_GIC_CPUI_BASE`] | `3ffd_0000` | `3fff_0000` | 128 KiB | vGIC | | [`AARCH64_GIC_DIST_BASE`] | `3fff_0000` | `4000_0000` | 64 KiB | vGIC | | [`AARCH64_AXI_BASE`] | `4000_0000` | | | Seemingly unused? Is this hard-coded somewhere in the kernel? | | [`AARCH64_PROTECTED_VM_FW_START`] | `7fc0_0000` | `8000_0000` | 4 MiB | pVM firmware (if running a protected VM) | | [`AARCH64_PHYS_MEM_START`] | `8000_0000` | | --mem size | RAM (starts at IPA = 2 GiB) | | [`get_swiotlb_addr`] | after RAM | | --swiotlb size | Only present for hypervisors requiring static swiotlb alloc | | [`plat_mmio_base`] | after swiotlb | +0x800000 | 8 MiB | Platform device MMIO region | | [`high_mmio_base`] | after plat_mmio | max phys addr | | High MMIO allocation area | ### Layout when booting a kernel These apply when no bootloader is passed, so crosvm boots a kernel directly. | Name/source link | Address | End (exclusive) | Size | Notes | | ------------------------- | ----------------- | --------------- | ----- | ---------------------------- | | [`AARCH64_KERNEL_OFFSET`] | `8000_0000` | | | Kernel load location in RAM | | [`initrd_addr`] | after kernel | | | Linux initrd location in RAM | | [`fdt_address`] | before end of RAM | | 2 MiB | Flattened device tree in RAM | ### Layout when booting a bootloader These apply when a bootloader is passed with `--bios`. | Name/source link | Address | End (exclusive) | Size | Notes | | ----------------------------------- | ----------- | --------------- | ----- | ---------------------------- | | [`AARCH64_FDT_OFFSET_IN_BIOS_MODE`] | `8000_0000` | `8020_0000` | 2 MiB | Flattened device tree in RAM | | [`AARCH64_BIOS_OFFSET`] | `8020_0000` | | | Bootloader image in RAM | [serial_addr]: https://crsrc.org/o/src/platform/crosvm/arch/src/serial.rs;l=78?q=SERIAL_ADDR [`aarch64_rtc_addr`]: https://crsrc.org/o/src/platform/crosvm/aarch64/src/lib.rs;l=177?q=AARCH64_RTC_ADDR [`aarch64_vmwdt_addr`]: https://crsrc.org/o/src/platform/crosvm/aarch64/src/lib.rs;l=187?q=AARCH64_VMWDT_ADDR [`aarch64_pci_cfg_base`]: https://crsrc.org/o/src/platform/crosvm/aarch64/src/lib.rs;l=192?q=AARCH64_PCI_CFG_BASE [`aarch64_mmio_base`]: https://crsrc.org/o/src/platform/crosvm/aarch64/src/lib.rs;l=196?q=AARCH64_MMIO_BASE [`aarch64_gic_cpui_base`]: https://crsrc.org/o/src/platform/crosvm/devices/src/irqchip/kvm/aarch64.rs;l=106?q=AARCH64_GIC_CPUI_BASE [`aarch64_gic_dist_base`]: https://crsrc.org/o/src/platform/crosvm/aarch64/src/lib.rs;l=105?q=AARCH64_GIC_DIST_BASE [`aarch64_axi_base`]: https://crsrc.org/o/src/platform/crosvm/aarch64/src/lib.rs;l=86?q=AARCH64_AXI_BASE [`aarch64_pvtime_ipa_start`]: https://crsrc.org/o/src/platform/crosvm/aarch64/src/lib.rs;l=100?q=AARCH64_PVTIME_IPA_START [`aarch64_protected_vm_fw_start`]: https://crsrc.org/o/src/platform/crosvm/aarch64/src/lib.rs;l=96?q=AARCH64_PROTECTED_VM_FW_START [`aarch64_phys_mem_start`]: https://crsrc.org/o/src/platform/crosvm/aarch64/src/lib.rs;l=85?q=AARCH64_PHYS_MEM_START [`get_swiotlb_addr`]: https://crsrc.org/o/src/platform/crosvm/aarch64/src/lib.rs?q=get_swiotlb_addr [`plat_mmio_base`]: https://crsrc.org/o/src/platform/crosvm/aarch64/src/lib.rs;l=835?q=plat_mmio_base [`high_mmio_base`]: https://crsrc.org/o/src/platform/crosvm/aarch64/src/lib.rs;l=838?q=high_mmio_base [`aarch64_kernel_offset`]: https://crsrc.org/o/src/platform/crosvm/aarch64/src/lib.rs;l=76?q=AARCH64_KERNEL_OFFSET [`initrd_addr`]: https://crsrc.org/o/src/platform/crosvm/aarch64/src/lib.rs;l=409?q=initrd_addr [`fdt_address`]: https://crsrc.org/o/src/platform/crosvm/aarch64/src/lib.rs;l=301?q=fdt_address [`aarch64_fdt_offset_in_bios_mode`]: https://crsrc.org/o/src/platform/crosvm/aarch64/src/lib.rs;l=90?q=AARCH64_FDT_OFFSET_IN_BIOS_MODE [`aarch64_bios_offset`]: https://crsrc.org/o/src/platform/crosvm/aarch64/src/lib.rs;l=92?q=AARCH64_BIOS_OFFSET