PXE Boot Menu Generator

Network boot menus sit before the installed operating system has a chance to protect, log, or recover the machine. In a Preboot Execution Environment, or PXE, firmware obtains an initial boot file from the network, then a bootloader menu chooses the next action. That action may start an unattended installer, load a rescue image, run diagnostics, return to the local disk, reboot, or hand control to another boot script.

The menu is small, but the consequences are not. A default installer entry can rebuild a host after a short timeout. A missing initial RAM disk can leave a rescue image without the early files it needs. A kernel argument copied from one distribution can be ignored by another. A chain target that works in iPXE may not work from a legacy PXELINUX path without the expected module or network support.

PXELINUX, iPXE, and GRUB often appear in the same boot estate because they serve different client classes and deployment habits. PXELINUX is common for legacy BIOS network boot, iPXE is useful for scripted menus and HTTP-served assets, and GRUB is a familiar UEFI menu format. Their menu labels may describe the same boot plan, but their syntax differs for defaults, timeouts, path resolution, chainloading, and initrd handling.

Generated menu text should be treated as a controlled draft, not proof that a machine will boot. DHCP options, TFTP roots, HTTP paths, bootloader modules, Secure Boot policy, firmware quirks, and installer-specific arguments all live outside the text. The safer workflow is to make the menu internally consistent, review the default and fallback behavior, then test on the real client class before production use.

How to Use This Tool:

Start with the boot plan, then use the review output to catch mismatched IDs, missing targets, and bootloader-specific assumptions before copying a menu into a boot-server workflow.

1. Enter Menu title with the environment, rack, lab, or build lane name operators should see during network boot.
2. Choose Selected menu format. This controls the summary copy button, while PXELINUX Menu, iPXE Script, and GRUB UEFI Menu remain available as separate result tabs when validation passes.
3. Set Default entry ID to the entry that should run after the timeout.
   If the summary changes to Fix menu inputs, open PXE Validation Review and compare the requested default with the IDs in Boot Entry Ledger.
4. Set Menu timeout in seconds. The generated formats convert that value to PXELINUX tenths of a second, iPXE milliseconds, or GRUB seconds.
5. Fill Boot entry rows using the eight-column order id,title,type,kernel-or-target,initrd,arguments,category,shortcut. Quote the arguments cell when it contains commas.
6. Use Ubuntu sample or Mixed sample when you need a starting shape, then use Normalize rows after pasting to rewrite the parsed rows into consistent CSV text.
7. Open Advanced for bootloader-specific choices such as iPXE asset base URL, PXELINUX menu module, PXELINUX initrd style, GRUB kernel commands, DHCP retry, local boot fallback, and reboot fallback.
   Relative iPXE image paths need an asset base when kernels and initrds are not served from the same directory as the script.
8. Read PXE Validation Review before using generated text. Errors block output. Warnings still allow output, but they name assumptions that need a real environment check.

Interpreting Results:

The most important result is whether the review found a blocking mismatch between the intended boot plan and the rows that were parsed. If Fix menu inputs appears, the code tabs stay empty until the listed error is corrected.

Do not treat matching PXELINUX, iPXE, and GRUB outputs as proof of equivalent runtime behavior. The text can be internally consistent while one client class still fails because a module is missing, a relative path resolves differently, or a firmware build does not support the chosen chainloading path.

Technical Details:

The row parser accepts non-empty, non-comment CSV lines and reads up to eight cells from each row. Entry IDs are normalized into compact labels, unsupported entry types are reported as errors, and duplicate IDs block output because labels and menu identifiers must be unique. The supported entry types are linux, chain, local, and reboot.

Linux entries need a kernel path and may include an initrd path plus kernel arguments. Chain entries need a target, such as another script or boot object. Local and reboot entries can be entered manually, or appended through the fallback switches. The generated fallback IDs are local-disk and reboot when those IDs are not already present.

Transformation Core:

Format Mapping:

Timeout Conversion:

The timeout input is entered once in seconds and converted to the unit each generated format expects. Values are clamped to a range from 0 to 86400 seconds before conversion.

With s = 8, PXELINUX receives TIMEOUT 80, iPXE receives --timeout 8000, and GRUB receives set timeout=8. A zero timeout is not identical across formats: PXELINUX disables the timeout, iPXE omits the choose timeout and waits indefinitely, while GRUB set timeout=0 boots the default immediately.

Validation Scope:

The review is a syntax and planning check. It catches empty row sets, rows with too many CSV cells, unsupported types, duplicate IDs, missing Linux kernels, missing chain targets, default IDs that do not match parsed entries, non-simple shortcut keys, initrd duplication, whitespace in paths, chain-entry risk, and missing iPXE asset base URLs. It does not verify that files exist, that a server can deliver them, that a bootloader module is present, that firmware accepts the commands, or that an installer understands the kernel arguments.

Limitations and Privacy Notes:

The generated menus are configuration drafts for review and lab testing. They should not be treated as deployment records or live boot-server checks.

• Validation does not contact DHCP, TFTP, HTTP, firmware, or bootloader services. A clean review only means the current rows can be rendered consistently.
• Kernel arguments are passed through as text. Distribution-specific installer options, kickstart paths, autoinstall data, and rescue flags still need target-image testing.
• The page builds output from values in the browser after it loads. Do not paste secrets into kernel arguments, asset paths, or chain targets unless the same values are already safe to place in boot-server configuration.

Worked Examples:

Ubuntu autoinstall default

A row such as ubuntu-autoinstall,Ubuntu Server autoinstall,linux,ubuntu/vmlinuz,ubuntu/initrd,ip=dhcp autoinstall,Installers,u creates a Linux entry with a kernel, initrd, installer arguments, category, and shortcut. With Default entry ID set to ubuntu-autoinstall and Menu timeout set to 8, the summary should report that ID as the default, and PXE Validation Review should include a pass row for the default entry.

Mixed menu with a chain target

A mixed set can include a Linux kickstart row, a chain row such as ipxe-tools,Chain to tools script,chain,scripts/tools.ipxe,,,Utilities,t, plus local boot and reboot fallbacks. The iPXE Script can jump to the chained script, while PXE Validation Review warns that chain targets need bootloader-specific testing.

Default ID typo

If the rows contain debian-rescue but Default entry ID is debian-rescue-shell, the summary changes to Fix menu inputs. PXE Validation Review reports that the default ID does not match a parsed entry, and the code tabs stay empty until the default is changed to an ID shown in Boot Entry Ledger.

Initrd conflict

A Linux row with an initrd cell and an argument string that already includes initrd=custom.img still generates menu text, but the review warns about duplicate initrd sources. Check Boot Entry Ledger and the selected output format, then keep either the separate initrd value or the explicit kernel argument so the booted kernel receives the intended early boot image.

FAQ:

Glossary:

PXE

Preboot Execution Environment, a firmware boot method that starts a machine from network-provided boot files.

PXELINUX

A Syslinux-family bootloader commonly used for legacy BIOS network boot menus.

iPXE

A scriptable network boot environment that can load kernels, initrds, and chained scripts from URIs.

GRUB UEFI

A GRUB menu path commonly used in UEFI boot flows.

Initrd

An initial RAM disk loaded with a Linux kernel to provide early boot files, drivers, or installer logic.

Chain entry

A menu entry that hands control to another boot image or script instead of directly loading a Linux kernel.

References:

• Config, Syslinux Wiki.
• PXELINUX, Syslinux Wiki.
• choose command, iPXE project.
• kernel command, iPXE project.
• menuentry, GNU GRUB Manual.
• timeout, GNU GRUB Manual.