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https://github.com/subhobhai943/SUB-OS.git
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Claude
a14a7c79b0
Replace the state-relabel-only round-robin with the SUB-OS "Weave" scheduler backed by a genuine callee-saved context switch. Threads now actually run on their own kernel stacks instead of merely having their state field rewritten. What was implemented: - sub_ctx_switch(): per-arch assembly (arch/x86_64/cpu/switch.asm, arch/aarch64/cpu/switch.S, arch/armv8i/cpu/switch.S) that saves/restores the callee-saved register set (+ flags on x86_64) on each thread's own stack, plus a first-run trampoline (sub_thread_trampoline) that launches a freshly forged thread frame with entry/arg in callee-saved registers. - task_forge_frame(): builds the initial saved-context frame per arch so the very first switch into a new thread lands on the trampoline; task_t gains a pointer-sized ctx_sp so the same struct works on 64- and 32-bit. - Weave policy (kernel/sched.c): WEAVE_NLANES priority lanes, always dispatch the lowest non-empty lane round-robin; a task that yields voluntarily is woven UP a lane (interactive), one preempted after burning its quantum is woven DOWN (CPU-bound). Cooperative switching (sched_yield / task_exit) is always live; timer-driven preemption is gated behind sched_set_preempt() and left disarmed for now. - task_exit() now switches to the next runnable thread via sched_exit_current() instead of spinning/halting. - Boot-time weave_selftest() (x86_64) and sched_dump() diagnostics. How it was verified: - Builds clean for all three targets: x86_64 (CROSS_COMPILE=x86_64-linux-gnu-, RUSTC="rustc --target x86_64-unknown-none"), aarch64, armv8i. No new warnings; the new x86_64 asm carries a .note.GNU-stack section. - Booted x86_64 under QEMU (TCG): the self-test runs three cooperative kernel threads to completion on separate stacks with the expected 1->2->3 round-robin interleave, reports "20 real context switches, 3/3 workers exited", returns cleanly to the boot thread, and boot proceeds normally to ring-3 init and the shell. No fault/panic. Left unverified: - The aarch64/armv8i sub_ctx_switch frames build and link but are not yet boot-tested on their QEMU targets (tracked in docs/AUTODEV_ROADMAP.md). - Timer preemption path is implemented but disarmed; exited kernel threads currently leak their stack (reaper is next in the backlog). Co-Authored-By: Claude Opus 4.8 <[email protected]> Claude-Session: https://claude.ai/code/session_01Jk6K69yGS7zYgvoWd6nJxQ
60 lines
1.6 KiB
C
60 lines
1.6 KiB
C
#ifndef _KERNEL_TASK_H
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#define _KERNEL_TASK_H
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#include "types.h"
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#include <lib/list.h>
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typedef enum {
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TASK_STATE_READY,
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TASK_STATE_RUNNING,
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TASK_STATE_BLOCKED,
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TASK_STATE_SLEEPING,
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TASK_STATE_ZOMBIE,
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TASK_STATE_DEAD
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} task_state_t;
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typedef struct task_struct {
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pid_t pid;
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pid_t ppid;
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pid_t pgid;
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char name[32];
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task_state_t state;
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uint64_t rsp;
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uint64_t stack_base;
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size_t stack_size;
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uint64_t sleep_until_ticks;
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int priority;
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int time_slice;
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int exit_code;
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/* --- SUB-OS "Weave" scheduler context ---------------------------------
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* ctx_sp is the saved stack pointer handed to sub_ctx_switch(); it is
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* pointer-sized so the same struct works on 64- and 32-bit targets.
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* A task lives in exactly one lane while it is runnable; weave_credit is
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* the quantum it has left in that lane, and weave_on marks it as an active
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* participant in the run rotation (so a bare kernel idle task that merely
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* calls sched_yield() is never enqueued). */
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void* ctx_sp;
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uint32_t weave_lane;
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uint32_t weave_credit;
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uint64_t sched_runs;
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uint8_t weave_on;
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struct list_head list;
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struct list_head all_list;
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} task_t;
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typedef void (*task_entry_fn_t)(void* arg);
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void task_init_idle(void);
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task_t* task_create(const char* name, task_entry_fn_t entry, void* arg, int priority);
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void task_exit(int exit_code);
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task_t* task_current(void);
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pid_t task_get_pid(void);
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void task_set_current(task_t* task);
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task_t* task_find_by_pid(pid_t pid);
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int task_kill(pid_t pid, int sig);
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void task_dump_pstree(void);
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#endif // _KERNEL_TASK_H
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