Messages in this thread Patch in this message |  | | Date | Thu, 3 May 2001 19:23:36 +0200 | From | Andrea Arcangeli <> | Subject | Re: [BUG] freeze Alpha ES40 SMP 2.4.4.ac3, another TCP/IP Problem ? ( was 2.4.4 kernel crash , possibly tcp related ) |
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On Thu, May 03, 2001 at 06:46:10PM +0200, Andrea Arcangeli wrote: > as well. The only annoying thing is that UP kernel compiles seems not to > boot but I hope that will be fixed soon too.
Ok I spotted and fixed that bug that forbidden my tree to boot with UP compiles on alpha. The bug is that the SCHED_YIELD handling was broken on alpha UP, this is the fix:
--- 2.4.5pre1aa1/arch/alpha/kernel/entry.S.~1~ Thu May 3 18:22:13 2001 +++ 2.4.5pre1aa1/arch/alpha/kernel/entry.S Thu May 3 19:18:16 2001 @@ -709,16 +709,14 @@ br restore_all .end entSys -#ifdef CONFIG_SMP - .globl ret_from_smp_fork + .globl ret_from_fork .align 3 -.ent ret_from_smp_fork -ret_from_smp_fork: +.ent ret_from_fork +ret_from_fork: lda $26,ret_from_sys_call mov $17,$16 jsr $31,schedule_tail -.end ret_from_smp_fork -#endif /* CONFIG_SMP */ +.end ret_from_fork .align 3 .ent reschedule --- 2.4.5pre1aa1/arch/alpha/kernel/process.c.~1~ Thu May 3 18:22:09 2001 +++ 2.4.5pre1aa1/arch/alpha/kernel/process.c Thu May 3 19:15:41 2001 @@ -306,7 +306,7 @@ struct task_struct * p, struct pt_regs * regs) { extern void ret_from_sys_call(void); - extern void ret_from_smp_fork(void); + extern void ret_from_fork(void); struct pt_regs * childregs; struct switch_stack * childstack, *stack; @@ -325,11 +325,7 @@ stack = ((struct switch_stack *) regs) - 1; childstack = ((struct switch_stack *) childregs) - 1; *childstack = *stack; -#ifdef CONFIG_SMP - childstack->r26 = (unsigned long) ret_from_smp_fork; -#else - childstack->r26 = (unsigned long) ret_from_sys_call; -#endif + childstack->r26 = (unsigned long) ret_from_fork; p->thread.usp = usp; p->thread.ksp = (unsigned long) childstack; p->thread.pal_flags = 1; /* set FEN, clear everything else */
(SCHED_YIELD of the previous task is cleared by __schedule_tail, it wasn't cleared so a non running task had a SCHED_YIELD set and it was deadlocking, this can explain many malfunction of UP alpha kernels) I never noticed so far because I always compiled it SMP.
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