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Yusuke Hirotavanou
Yusuke Hirota
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vanou
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add section "Boot loader management and file structure" to appendix
When users install Foreman and Smart Proxy using foreman-installer, PXE bootloader binaries are automatically deployed under /var/lib/tftpboot/. However, users who handle non-x86 architectures (for example, Arm or PowerPC), or who install these components manually, often find the following points unclear: - Which bootloader binaries should be placed under which directories - How the bootloader-universe/ structure should be organized - How these files correspond to architectures and operating systems defined in the Foreman Web UI This commit adds a new appendix section titled "Boot loader management and file structure" to the Provisioning Hosts guide. The appendix explains: 1. The structure and purpose of /var/lib/tftpboot/ and bootloader-universe/ 2. Where to place PXE bootloader binaries for GRUB2, PXELinux, and iPXE 3. How symbolic links are automatically created for each host at build time This documentation helps users correctly prepare and manage PXE bootloader files for both x86 and non-x86 environments. Co-Authored-By: Vanou Ishii <[email protected]>
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‎guides/common/assembly_bootloader-binary-location.adoc‎

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:_mod-docs-content-type: ASSEMBLY
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include::modules/con_bootloader-binary-location-overview.adoc[]
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include::modules/ref_bootloader-types.adoc[leveloffset=+1]
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include::modules/ref_pxelinux-bootloaders.adoc[leveloffset=+1]
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include::modules/ref_grub2-uefi-bootloaders.adoc[leveloffset=+1]
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include::modules/ref_ipxe-bootloaders.adoc[leveloffset=+1]

‎guides/common/modules/con_bootloader-binary-location-overview.adoc‎

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:_mod-docs-content-type: CONCEPT
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[id="con_bootloader-binary-location-overview_{context}"]
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= Boot loader management and file structure
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This section describes how {Project} manages and serves boot loader binaries through the *{SmartProxy}*, which provides the underlying network boot services used during automated host provisioning.
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While traditional *PXE (Preboot Execution Environment)* remains a core method, {Project} also supports *HTTPBoot*, *iPXE*, and *UEFI HTTP(S) Boot* mechanisms.
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During a network-based installation, {SmartProxy} coordinates multiple services:
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* DHCP: Assigns IP addresses and provides the boot loader filename and `next-server` information.
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* TFTP: Delivers boot loaders such as PXELinux, GRUB, or iPXE binaries to clients.
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* HTTP(S): Serves boot loaders and installation images via the {SmartProxy}’s HTTPBoot module
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When a host begins a network boot, it retrieves the appropriate boot loader (for example, `pxelinux.0`, `grubx64.efi`, or `ipxe.efi`) according to its firmware type and *PXE Loader* setting in {Project}.
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The boot loader then loads {Project}-generated configuration files that define which kernel and initrd to boot, initiating the OS installation process.
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The *{SmartProxy}* manages the distribution of these boot loader binaries and configuration files.
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All boot loaders, whether used for PXE, iPXE, or HTTPBoot, are stored under the {SmartProxy}’s TFTP root directory (`/var/lib/tftpboot/`), which is also shared by the HTTPBoot service.
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Each boot loader binary is organized within a directory structure based on its type, architecture, and operating system version.
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[NOTE]
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====
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The TFTP root directory is configured in `/etc/foreman-proxy/settings.d/tftp.yml` under the `:tftproot` parameter.
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In this document, the default path `/var/lib/tftpboot` is used for explanation.
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If your environment uses a different path, please substitute it accordingly.
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The directory used by *Grub2 UEFI HTTP* and *iPXE HTTP* for file delivery is defined in `/etc/foreman-proxy/settings.d/httpboot.yml` under the `:root_dir` parameter.
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This also defaults to `/var/lib/tftpboot`.
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If you have customized this setting, read the descriptions in this section using your configured directory path instead.
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====
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‎guides/common/modules/ref_bootloader-types.adoc‎

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:_mod-docs-content-type: REFERENCE
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[id="ref_bootloader-types_{context}"]
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= Boot loader types in {Project}
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This section describes the PXE boot loaders supported by {Project} and explains how each type is used during network provisioning, depending on firmware type, protocol, and boot environment.
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{Project} allows you to configure a **PXE Loader** for each host.
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The PXE Loader determines which boot loader binary the host retrieves during network boot and how it communicates with the {SmartProxy} (via TFTP or HTTP).
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Selection depends on whether the host uses **BIOS**, **UEFI**, **Secure Boot**, or **HTTP Boot**.
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== PXE Loader Types and Boot Protocols in {Project}
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The following table lists the PXE Loader options available in the {Project}.
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Each loader is associated with a specific boot protocol and firmware type.
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. PXE Loader Types and Boot Protocols
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[cols="1,1,1,1", options="header"]
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|===
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| PXE Loader (UI Label)
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| Category
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| Firmware
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| Protocol
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| None
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| None
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| -
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| -
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| PXELinux BIOS
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| PXELinux
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| BIOS
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| DHCP → TFTP
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| PXELinux UEFI
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| PXELinux
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| UEFI
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| DHCP → TFTP
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| Grub UEFI
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| PXEGrub (Legacy)
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| UEFI
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| DHCP → TFTP
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| Grub2 BIOS
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| PXEGrub2 (TFTP)
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| BIOS
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| DHCP → TFTP
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| Grub2 ELF
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| PXEGrub2 (TFTP)
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| BIOS
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| DHCP → TFTP
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| Grub2 UEFI
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| PXEGrub2 (TFTP)
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| UEFI
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| DHCP → TFTP
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| Grub2 UEFI SecureBoot
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| PXEGrub2 (TFTP)
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| UEFI
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| DHCP → TFTP
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| Grub2 UEFI HTTP
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| Grub2 (HTTP)
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| UEFI
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| DHCP → HTTP
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| Grub2 UEFI HTTPS
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| Grub2 (HTTPS)
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| UEFI
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| DHCP → HTTPS
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| Grub2 UEFI HTTPS SecureBoot
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| Grub2 (HTTPS)
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| UEFI
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| DHCP → HTTPS
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| iPXE Embedded
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| iPXE Direct (HTTP)
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| BIOS / UEFI
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| DHCP → HTTP
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| iPXE UEFI HTTP
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| iPXE Direct (HTTP)
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| UEFI
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| DHCP → HTTP
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| iPXE Chain BIOS
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| iPXE Chainload
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| BIOS
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| DHCP → TFTP → HTTP
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| iPXE Chain UEFI
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| iPXE Chainload
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| UEFI
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| DHCP → TFTP → HTTP
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|===
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This table lists the available PXE Loader categories and describes how each type delivers boot loaders and installation files during network provisioning.
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. PXE Loader categories
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[cols="30%,70%",options="header"]
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|===
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| Category | Description
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| PXELinux
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| Syslinux-based loaders for BIOS and UEFI environments.
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| PXEGrub (Legacy)
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| Early GRUB-based loader for UEFI systems.
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| PXEGrub2 (TFTP)
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| GRUB2-based loader supporting both BIOS and UEFI environments (including Secure Boot via `shim`).
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| Grub2 (HTTP/HTTPS)
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| GRUB2-based UEFI boot loader fetched over HTTP or HTTPS using the {SmartProxy}’s HTTPBoot service.
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| iPXE Chainload
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| A two-stage boot process in which the client first downloads an iPXE binary (`undionly-ipxe.0` or `ipxe.efi`) via TFTP.
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Once loaded, iPXE retrieves {Project}’s iPXE script and installation files over HTTP, enabling flexible configuration and network boot via HTTP.
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| iPXE Direct (HTTP)
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| Boots directly via embedded or firmware-level iPXE using only HTTP.
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| None
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| {Project} does not specify a boot loader.
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|===
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== Boot Loader File Mapping and Architecture Naming
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{Project} automatically determines the correct boot loader filename for each host based on its *architecture* and the *PXE Loader* selected in the host settings.
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This mechanism ensures that the correct boot loader binary (such as `grubx64.efi` or `grubaa64.efi`) is selected automatically,
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without requiring administrators to manage architecture-specific filenames.
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.PXE Loader to Boot Loader Mapping
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[cols="1,1,1", options="header"]
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|===
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| PXE Loader (UI Label)
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| Boot Loader File (Template Path)
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| Example (x86_64)
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| None
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| -
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| -
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| PXELinux BIOS
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| pxelinux.0
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| pxelinux.0
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| PXELinux UEFI
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| pxelinux.efi
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| pxelinux.efi
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| Grub2 BIOS
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| grub<__arch__>.0
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| grubx64.0
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| Grub2 ELF
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| grub<__arch__>.elf
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| grubx64.elf
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| Grub2 UEFI
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| grub<__arch__>.efi
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| grubx64.efi
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| Grub2 UEFI SecureBoot
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| shim<__arch__>.efi
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| shimx64.efi
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| Grub2 UEFI HTTP
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| grub<__arch__>.efi (via HTTP)
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| grubx64.efi
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| Grub2 UEFI HTTPS
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| grub<__arch__>.efi (via HTTPS)
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| grubx64.efi
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| Grub2 UEFI HTTPS SecureBoot
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| shim<__arch__>.efi (via HTTPS)
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| shimx64.efi
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| iPXE Embedded
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| Rendered dynamically as {Project}_url('iPXE')
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| -
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| iPXE UEFI HTTP
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| ipxe-<__arch__>.efi
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| ipxe-x64.efi
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| iPXE Chain BIOS
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| undionly-ipxe.0
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| undionly-ipxe.0
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| iPXE Chain UEFI
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| ipxe.efi
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| ipxe.efi
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|===
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== Architecture-Based File Naming
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{Project} automatically determines the correct boot loader filename for each host based on its architecture.
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For example, `x86_64` hosts use `grubx64.efi`, while `aarch64` hosts use `grubaa64.efi`.
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.Boot Loader Filenames by Architecture
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[cols="1,1,1", options="header"]
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|===
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| Architecture (Web UI)
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| Example Filename
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| Internal Suffix (for reference)
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| i386, i686, x86
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| grubia32.efi
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| ia32
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| x86_64, amd64
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| grubx64.efi, shimx64.efi
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| x64
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| aarch64, aa64
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| grubaa64.efi, shimaa64.efi
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| aa64
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| ppc64, ppc64le
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| grubppc64.efi
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| ppc64, ppc64le
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| Other architectures (for example, riscv64, loongarch64)
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| grubriscv64.efi
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| normalized name
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|===
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For instance, a host with architecture `aarch64` and PXE Loader set to “Grub2 UEFI” will use:
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----
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/var/lib/tftpboot/grub2/grubaa64.efi
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----
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This mechanism allows {Project} to select the correct boot loader automatically,
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without requiring users to manage architecture-specific filenames manually.

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