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Linux 7.0 unified deadline.c into build_policy.c and debug.c into build_utility.c, deleting the historical CONFIG_SCHED_DEADLINE and CONFIG_SCHED_DEBUG knobs. On a NOMMU image with no /proc/<pid>/sched reader, no debugfs sched-domain consumer, no sysrq input device, and no SCHED_DEADLINE userspace, the two files are ~14.8KB of dead .text that no Kconfig flip can reach. Reintroduce the gates as out-of-tree patches: SCHED_DEBUG_OUTPUT and SCHED_DEADLINE_CLASS, both default y. When n, each file's body is wrapped in #ifdef and a stub block at the same path provides empty implementations of every externally-called symbol. Stub dl_sched_class is registered via DEFINE_SCHED_CLASS(dl) so it lands in the __dl_sched_class linker section between stop and rt; the C99 sparse initializer still reserves the full 116-byte struct, zero-filling every callback except .pick_task (which returns NULL so the chain walk falls through to fair). __checkparam_dl returns false so sched_setattr with policy=6 fails admission and no task ever joins the class. Build.sh disables the new symbols and a small cluster of dependent knobs (CGROUPS, PSI, SCHED_AUTOGROUP) that share the same audience on a single-rootfs UP target. The post-olddefconfig verifier covers both new symbols positively and the cgroup/SMP-dependent siblings negatively, so a future Kconfig drift that flips any of them back to =y aborts the build loudly instead of silently regressing the image. Measured: vmlinux .text -18,240 (-2.4%), .rodata -1,920 (-1.6%), linux.axf 1,229,344 -> 1,212,960 (-16,384 / -1.33%). QEMU MPS2-AN386 boots clean to BusyBox shell, dmesg has no warn/bug/oops/null. The canonical mirror at downloads.uclibc-ng.org has been returning HTTP 522 (Cloudflare-to-origin failure) for extended windows, breaking CI on a fresh downloads cache (wget exits 8, no useful diagnostic under QUIET=1). GitHub's tag-based source archive is permanent for a fixed (repo, tag) pair and contains the same 5,527-file tree as the upstream release tarball -- verified by extracting both and comparing the concat-and-hash of all file contents.
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Linux 7.0 unified deadline.c into build_policy.c and debug.c into build_utility.c, deleting the historical CONFIG_SCHED_DEADLINE and CONFIG_SCHED_DEBUG knobs. On a NOMMU image with no /proc//sched reader, no debugfs sched-domain consumer, no sysrq input device, and no SCHED_DEADLINE userspace, the two files are ~14.8KB of dead .text that no Kconfig flip can reach.
Reintroduce the gates as out-of-tree patches: SCHED_DEBUG_OUTPUT and SCHED_DEADLINE_CLASS, both default y. When n, each file's body is wrapped in #ifdef and a stub block at the same path provides empty implementations of every externally-called symbol. Stub dl_sched_class is registered via DEFINE_SCHED_CLASS(dl) so it lands in the __dl_sched_class linker section between stop and rt; the C99 sparse initializer still reserves the full 116-byte struct, zero-filling every callback except .pick_task (which returns NULL so the chain walk falls through to fair). __checkparam_dl returns false so sched_setattr with policy=6 fails admission and no task ever joins the class.
Build.sh disables the new symbols and a small cluster of dependent knobs (CGROUPS, PSI, SCHED_AUTOGROUP) that share the same audience on a single-rootfs UP target. The post-olddefconfig verifier covers both new symbols positively and the cgroup/SMP-dependent siblings negatively, so a future Kconfig drift that flips any of them back to =y aborts the build loudly instead of silently regressing the image.
Measured: vmlinux .text -18,240 (-2.4%), .rodata -1,920 (-1.6%), linux.axf 1,229,344 -> 1,212,960 (-16,384 / -1.33%). QEMU MPS2-AN386 boots clean to BusyBox shell, dmesg has no warn/bug/oops/null.