Date: Fri, 27 May 2011 14:27:28 +0000 (UTC) From: Nathan Whitehorn <nwhitehorn@FreeBSD.org> To: src-committers@freebsd.org, svn-src-projects@freebsd.org Subject: svn commit: r222356 - projects/pseries/kern Message-ID: <201105271427.p4RERSUb039281@svn.freebsd.org>
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Author: nwhitehorn Date: Fri May 27 14:27:28 2011 New Revision: 222356 URL: http://svn.freebsd.org/changeset/base/222356 Log: On multi-core, multi-threaded PPC systems, it is important that the threads be brought up in the order they are enumerated in the device tree (in particular, that thread 0 on each core be brought up first). The SLIST through which we loop to start the CPUs has all of its entries added with SLIST_INSERT_HEAD(), which means it is in reverse order of enumeration and so AP startup would always fail in such situation (causing a machine check or RTAS failure). The best fix is probably to change this from a LIST to a TAILQ, but fix this by looping through to add new cpus to the end of the list. Modified: projects/pseries/kern/subr_pcpu.c Modified: projects/pseries/kern/subr_pcpu.c ============================================================================== --- projects/pseries/kern/subr_pcpu.c Fri May 27 14:08:24 2011 (r222355) +++ projects/pseries/kern/subr_pcpu.c Fri May 27 14:27:28 2011 (r222356) @@ -82,6 +82,7 @@ struct cpuhead cpuhead = SLIST_HEAD_INIT void pcpu_init(struct pcpu *pcpu, int cpuid, size_t size) { + struct pcpu *tail; bzero(pcpu, size); KASSERT(cpuid >= 0 && cpuid < MAXCPU, @@ -89,7 +90,17 @@ pcpu_init(struct pcpu *pcpu, int cpuid, pcpu->pc_cpuid = cpuid; pcpu->pc_cpumask = 1 << cpuid; cpuid_to_pcpu[cpuid] = pcpu; - SLIST_INSERT_HEAD(&cpuhead, pcpu, pc_allcpu); + /* + * It may be important that the CPU list stay ordered, so try to + * install this PCPU at the end of the list instead of the beginnig. + */ + for (tail = SLIST_FIRST(&cpuhead); tail != NULL && + SLIST_NEXT(tail, pc_allcpu) != NULL; + tail = SLIST_NEXT(tail, pc_allcpu)) {} + if (tail != NULL) + SLIST_INSERT_AFTER(tail, pcpu, pc_allcpu); + else + SLIST_INSERT_HEAD(&cpuhead, pcpu, pc_allcpu); cpu_pcpu_init(pcpu, cpuid, size); pcpu->pc_rm_queue.rmq_next = &pcpu->pc_rm_queue; pcpu->pc_rm_queue.rmq_prev = &pcpu->pc_rm_queue;
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