kexec-iso-init: improve hybrid ISO detection and boot param handling#2083
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tlaurion wants to merge 3 commits intolinuxboot:masterfrom
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kexec-iso-init: improve hybrid ISO detection and boot param handling#2083tlaurion wants to merge 3 commits intolinuxboot:masterfrom
tlaurion wants to merge 3 commits intolinuxboot:masterfrom
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Pull request overview
Adds ISO-on-USB boot compatibility detection and improved UX/logging around kexec-based booting, including documentation of supported ISO behaviors.
Changes:
- Add initrd/GRUB scanning and USB filesystem compatibility checks for ISO-file boot, with user warnings on likely failures.
- Improve boot option selection UX and display of applied kernel parameter add/remove operations.
- Log the final kernel command line in debug output and document the ISO boot flow + compatibility matrix.
Reviewed changes
Copilot reviewed 1 out of 4 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| initrd/bin/kexec-select-boot.sh | Simplifies menu display and improves confirmation/add/remove parameter UX. |
| initrd/bin/kexec-iso-init.sh | Adds ISO boot-method detection, USB FS probing, initrd capability heuristics, and broader distro parameter support. |
| initrd/bin/kexec-boot.sh | Refactors option parsing and adds debug logging of the final kernel cmdline. |
| doc/boot-process.md | Documents “Stage 2b” ISO-on-USB boot flow and known compatibility results. |
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- Add check_hybrid_iso() using MBR signature at offset 510 (0x55AA) - Add detect_iso_boot_method() to extract boot params from initrd via strings - Add inspect_iso_boot_config() to extract boot params from GRUB configs - Simplify header to document Dracut vs Anaconda boot methods - Use DEBUG level for NOTE/WARN/STATUS spam per logging.md - Change terminal prompts to [Y,d] style with Enter defaulting to yes - Remove Anaconda blocking - let user attempt boot (Qubes R4.3 works) - Keep combined boot params approach (let ISO initrd pick what it needs) Tested with Qubes R4.3 on Q35 QEMU (works). Ref: linuxboot#2083, linuxboot#2008
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Apr 13, 2026
Add resolve_grub_vars() to substitute GRUB variables like ${iso_path}
and ${isofile} with the actual ISO path when extracting boot params
from GRUB configs.
Fixes boot failure where iso-scan/filename=${iso_path} wasn't being
resolved to the actual ISO path.
Ref: linuxboot#2083
Add resolve_grub_vars() to substitute GRUB variables like ${iso_path}
and ${isofile} with the actual ISO path when extracting boot params
from GRUB configs.
Fixes boot failure where iso-scan/filename=${iso_path} wasn't being
resolved to the actual ISO path.
Ref: linuxboot#2083
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Add TRACE/DEBUG to understand how boot parameters flow through kexec-boot.sh, especially the cmdline and cmdadd parameters. Ref: linuxboot#2083
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enhancement / improvement
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Summary
check_hybrid_iso()using MBR signature at offset 510 (0x55AA)detect_iso_boot_method()to extract boot params from initrd via stringsinspect_iso_boot_config()to extract boot params from GRUB configsresolve_grub_vars()to substitute GRUB variables like${iso_path}with actual ISO pathTesting
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