程序链接了DPDK库,启动就出错,打出如下信息: EAL: UIO_RESOURCE_LIST tailq is already registered PANIC in tailqinitfn_rte_uio_tailq(): Cannot initialize tailq: UIO_RESOURCE_LIST 分析发现,C语言定义constructor属性的函数会先于main()执行,DPDK中定义了RTE_INIT()宏,用来声明一个如构造函数:
#define RTE_PRIO(prio) \ RTE_PRIORITY_ ## prio /** * Run function before main() with high priority. * * @param func * Constructor function. * @param prio * Priority number must be above 100. * Lowest number is the first to run. */ #ifndef RTE_INIT_PRIO /* Allow to override from EAL */ #define RTE_INIT_PRIO(func, prio) \ static void __attribute__((constructor(RTE_PRIO(prio)), used)) func(void) #endif /** * Run function before main() with low priority. * * The constructor will be run after prioritized constructors. * * @param func * Constructor function. */ #define RTE_INIT(func) \ RTE_INIT_PRIO(func, LAST)
在tailq.h中定义了EAL_REGISTER_TAILQ()
/** * Register a tail queue. * * Register a tail queue from shared memory. * This function is mainly used by EAL_REGISTER_TAILQ macro which is used to * register tailq from the different dpdk libraries. Since this macro is a * constructor, the function has no access to dpdk shared memory, so the * registered tailq can not be used before call to rte_eal_init() which calls * rte_eal_tailqs_init(). * * @param t * The tailq element which contains the name of the tailq you want to * create (/retrieve when in secondary process). * @return * 0 on success or -1 in case of an error. */ int rte_eal_tailq_register(struct rte_tailq_elem *t); #define EAL_REGISTER_TAILQ(t) \ RTE_INIT(tailqinitfn_ ##t) \ { \ if (rte_eal_tailq_register(&t) < 0) \ rte_panic("Cannot initialize tailq: %s\n", t.name); \ }
然后用定义了很多初始化构造函数,比如rte_ring.c中:
#define RTE_TAILQ_RING_NAME "RTE_RING" static struct rte_tailq_elem rte_ring_tailq = { .name = RTE_TAILQ_RING_NAME, }; EAL_REGISTER_TAILQ(rte_ring_tailq)
所以原因是涉及到的constructor函数代码有多个实例,被重复调用。我遇到的实例是因为有重复静态链接:app链接了libxxx.a和librte_*.a, 并且libxxx.a也链接了librte_*.a,app里面就有两份librte_*.a的代码实例。
解决方法:把静态链接librte_*.a都改成动态链接librte_*.so
加入log,可发现在main()函数之前调用了很多EAL_REGISTER_TAILQ()函数:
EAL: rte_eal_tailq_register: name=RTE_RING
EAL: rte_eal_tailq_register: name=RTE_MEMPOOL
EAL: rte_eal_tailq_register: name=RTE_MBUF_DYNFIELD
EAL: rte_eal_tailq_register: name=RTE_MBUF_DYNFLAG
EAL: rte_eal_tailq_register: name=RTE_HASH
EAL: rte_eal_tailq_register: name=RTE_FBK_HASH
EAL: rte_eal_tailq_register: name=RTE_THASH
EAL: rte_eal_tailq_register: name=RTE_ACL
EAL: rte_eal_tailq_register: name=RTE_DIST_BURST
EAL: rte_eal_tailq_register: name=RTE_DISTRIBUTOR
EAL: rte_eal_tailq_register: name=RTE_EFD
EAL: rte_eal_tailq_register: name=RTE_KNI
EAL: rte_eal_tailq_register: name=RTE_LPM
EAL: rte_eal_tailq_register: name=RTE_LPM6
EAL: rte_eal_tailq_register: name=RTE_MEMBER
EAL: rte_eal_tailq_register: name=RTE_RIB
EAL: rte_eal_tailq_register: name=RTE_RIB6
EAL: rte_eal_tailq_register: name=RTE_REORDER
EAL: rte_eal_tailq_register: name=RTE_STACK
EAL: rte_eal_tailq_register: name=RTE_IPSEC_SAD
EAL: rte_eal_tailq_register: name=RTE_FIB
EAL: rte_eal_tailq_register: name=RTE_FIB6