Fix invalid THP kernel param in optimize_kernel (#176)

[VijitSingh97]

⛔ Merge order: goes after #114

Draft on purpose. This touches GRUB / kernel boot params, so it should be validated against the real-server end-to-end test harness in #114 before merging. Hold until #114 testing is done.

Fixes #176.

Problem

optimize_kernel appended transparent_hugepages=never (plural) to GRUB_CMDLINE_LINUX_DEFAULT. The real Linux kernel parameter is singular — transparent_hugepage=never. The plural form is an unrecognized param the kernel silently ignores, so disabling Transparent HugePages for RandomX never took effect even after the GRUB edit + reboot:

$ cat /sys/kernel/mm/transparent_hugepage/enabled
always [madvise] never     # distro default — NOT [never]

No error, no warning, and doctor doesn't check THP state — so it failed silently.

The explicit HugePages reservation (hugepagesz=2M hugepages=3072) was already correct and is unchanged — only the THP-disable was broken.

Fix

• Extract the boot params into a single randomx_boot_params helper (one source of truth, unit-testable) with the corrected singular param; optimize_kernel's edit now consumes it.
• Self-heal already-broken installs. A box that ran the buggy version has the plural token and hugepages= in GRUB, so the reservation guard (grep -q "hugepages=") would report "already configured" and skip — leaving the dead plural token in place forever. heal_grub_thp_typo rewrites it to the singular form (idempotent: a no-op once corrected) and re-runs update-grub.
• Stop silently no-op'ing the insert. The edit only handles the standard double-quoted GRUB_CMDLINE_LINUX_DEFAULT="..." line; previously a single-quoted / commented / absent line meant nothing changed yet update-grub still ran and a reboot was flagged. append_grub_boot_params now anchors to the active (non-comment) line, returns non-zero when there's nothing to edit, and the caller prints manual instructions instead of claiming success. The ^-anchor also stops a commented-out example line from being edited.
• Add sudo_sed (safe_sed's GNU/BSD -i split, with sudo) so the helpers are portable across the Linux target and a macOS dev box.

Confirmed on a live box: with the singular form + update-grub + reboot, /sys/kernel/mm/transparent_hugepage/enabled reads [never].

Test

bash tests/stack/run.sh → 125 passed, 0 failed. New assertions:

• unit: randomx_boot_params — generated cmdline reserves HugePages and uses the singular THP param; explicitly fails on the plural typo so it can't regress.
• unit: grub heal + boot-param insert — exercises the real heal/insert transforms via a passthrough-sudo stub against sandbox grub files: heal rewrites plural→singular and is an idempotent no-op once corrected; insert appends to the active line while preserving existing params; a commented-out line is left untouched and reported (no silent reboot).

shellcheck -S warning pithead tests/stack/run.sh → clean.

🤖 Generated with Claude Code