linux常用头文件之--linux/device.h

本文深入探讨了Linux内核中device.h文件提供的关键函数,包括设备创建、驱动注册、类创建、总线操作等功能,详细解释了每个函数的作用及使用场景,对于设备管理和驱动开发具有重要的指导意义。

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在device.h文件中 又给提供了那些函数呢?

在这个头文件中包含了 bus的一些函数 和 drifver的一些函数,以及class_create()等函数

/*源代码**/

/*
 * device.h - generic, centralized driver model
 *
 * Copyright (c) 2001-2003 Patrick Mochel <mochel@osdl.org>
 * Copyright (c) 2004-2009 Greg Kroah-Hartman <gregkh@suse.de>
 * Copyright (c) 2008-2009 Novell Inc.
 *
 * This file is released under the GPLv2
 *
 * See Documentation/driver-model/ for more information.
 */


#ifndef _DEVICE_H_
#define _DEVICE_H_


#include <linux/ioport.h>
#include <linux/kobject.h>
#include <linux/klist.h>
#include <linux/list.h>
#include <linux/lockdep.h>
#include <linux/compiler.h>
#include <linux/types.h>
#include <linux/module.h>
#include <linux/pm.h>
#include <asm/atomic.h>
#include <asm/device.h>


struct device;
struct device_private;
struct device_driver;
struct driver_private;
struct class;
struct subsys_private;
struct bus_type;
struct device_node;


struct bus_attribute {
struct attribute attr;
ssize_t (*show)(struct bus_type *bus, char *buf);
ssize_t (*store)(struct bus_type *bus, const char *buf, size_t count);
};


#define BUS_ATTR(_name, _mode, _show, _store) \
struct bus_attribute bus_attr_##_name = __ATTR(_name, _mode, _show, _store)


extern int __must_check bus_create_file(struct bus_type *,
struct bus_attribute *);
extern void bus_remove_file(struct bus_type *, struct bus_attribute *);


struct bus_type {
const char *name;
struct bus_attribute *bus_attrs;
struct device_attribute *dev_attrs;
struct driver_attribute *drv_attrs;


int (*match)(struct device *dev, struct device_driver *drv);
int (*uevent)(struct device *dev, struct kobj_uevent_env *env);
int (*probe)(struct device *dev);
int (*remove)(struct device *dev);
void (*shutdown)(struct device *dev);


int (*suspend)(struct device *dev, pm_message_t state);
int (*resume)(struct device *dev);


const struct dev_pm_ops *pm;


struct subsys_private *p;
};


extern int __must_check bus_register(struct bus_type *bus);
extern void bus_unregister(struct bus_type *bus);


extern int __must_check bus_rescan_devices(struct bus_type *bus);


/* iterator helpers for buses */


int bus_for_each_dev(struct bus_type *bus, struct device *start, void *data,
    int (*fn)(struct device *dev, void *data));
struct device *bus_find_device(struct bus_type *bus, struct device *start,
      void *data,
      int (*match)(struct device *dev, void *data));
struct device *bus_find_device_by_name(struct bus_type *bus,
      struct device *start,
      const char *name);


int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
    void *data, int (*fn)(struct device_driver *, void *));


void bus_sort_breadthfirst(struct bus_type *bus,
  int (*compare)(const struct device *a,
 const struct device *b));
/*
 * Bus notifiers: Get notified of addition/removal of devices
 * and binding/unbinding of drivers to devices.
 * In the long run, it should be a replacement for the platform
 * notify hooks.
 */
struct notifier_block;


extern int bus_register_notifier(struct bus_type *bus,
struct notifier_block *nb);
extern int bus_unregister_notifier(struct bus_type *bus,
  struct notifier_block *nb);


/* All 4 notifers below get called with the target struct device *
 * as an argument. Note that those functions are likely to be called
 * with the device lock held in the core, so be careful.
 */
#define BUS_NOTIFY_ADD_DEVICE 0x00000001 /* device added */
#define BUS_NOTIFY_DEL_DEVICE 0x00000002 /* device removed */
#define BUS_NOTIFY_BIND_DRIVER 0x00000003 /* driver about to be
     bound */
#define BUS_NOTIFY_BOUND_DRIVER 0x00000004 /* driver bound to device */
#define BUS_NOTIFY_UNBIND_DRIVER 0x00000005 /* driver about to be
     unbound */
#define BUS_NOTIFY_UNBOUND_DRIVER 0x00000006 /* driver is unbound
     from the device */


extern struct kset *bus_get_kset(struct bus_type *bus);
extern struct klist *bus_get_device_klist(struct bus_type *bus);


struct device_driver {
const char *name;
struct bus_type *bus;


struct module *owner;
const char *mod_name; /* used for built-in modules */


bool suppress_bind_attrs; /* disables bind/unbind via sysfs */


#if defined(CONFIG_OF)
const struct of_device_id *of_match_table;
#endif


int (*probe) (struct device *dev);
int (*remove) (struct device *dev);
void (*shutdown) (struct device *dev);
int (*suspend) (struct device *dev, pm_message_t state);
int (*resume) (struct device *dev);
const struct attribute_group **groups;


const struct dev_pm_ops *pm;


struct driver_private *p;
};




extern int __must_check driver_register(struct device_driver *drv);
extern void driver_unregister(struct device_driver *drv);


extern struct device_driver *get_driver(struct device_driver *drv);
extern void put_driver(struct device_driver *drv);
extern struct device_driver *driver_find(const char *name,
struct bus_type *bus);
extern int driver_probe_done(void);
extern void wait_for_device_probe(void);




/* sysfs interface for exporting driver attributes */


struct driver_attribute {
struct attribute attr;
ssize_t (*show)(struct device_driver *driver, char *buf);
ssize_t (*store)(struct device_driver *driver, const char *buf,
size_t count);
};


#define DRIVER_ATTR(_name, _mode, _show, _store) \
struct driver_attribute driver_attr_##_name = \
__ATTR(_name, _mode, _show, _store)


extern int __must_check driver_create_file(struct device_driver *driver,
const struct driver_attribute *attr);
extern void driver_remove_file(struct device_driver *driver,
      const struct driver_attribute *attr);


extern int __must_check driver_add_kobj(struct device_driver *drv,
struct kobject *kobj,
const char *fmt, ...);


extern int __must_check driver_for_each_device(struct device_driver *drv,
      struct device *start,
      void *data,
      int (*fn)(struct device *dev,
void *));
struct device *driver_find_device(struct device_driver *drv,
 struct device *start, void *data,
 int (*match)(struct device *dev, void *data));


/*
 * device classes
 */
struct class {
const char *name;
struct module *owner;


struct class_attribute *class_attrs;
struct device_attribute *dev_attrs;
struct bin_attribute *dev_bin_attrs;
struct kobject *dev_kobj;


int (*dev_uevent)(struct device *dev, struct kobj_uevent_env *env);
char *(*devnode)(struct device *dev, mode_t *mode);


void (*class_release)(struct class *class);
void (*dev_release)(struct device *dev);


int (*suspend)(struct device *dev, pm_message_t state);
int (*resume)(struct device *dev);


const struct kobj_ns_type_operations *ns_type;
const void *(*namespace)(struct device *dev);


const struct dev_pm_ops *pm;


struct subsys_private *p;
};


struct class_dev_iter {
struct klist_iter ki;
const struct device_type *type;
};


extern struct kobject *sysfs_dev_block_kobj;
extern struct kobject *sysfs_dev_char_kobj;
extern int __must_check __class_register(struct class *class,
struct lock_class_key *key);
extern void class_unregister(struct class *class);


/* This is a #define to keep the compiler from merging different
 * instances of the __key variable */
#define class_register(class) \
({ \
static struct lock_class_key __key; \
__class_register(class, &__key); \
})


struct class_compat;
struct class_compat *class_compat_register(const char *name);
void class_compat_unregister(struct class_compat *cls);
int class_compat_create_link(struct class_compat *cls, struct device *dev,
    struct device *device_link);
void class_compat_remove_link(struct class_compat *cls, struct device *dev,
     struct device *device_link);


extern void class_dev_iter_init(struct class_dev_iter *iter,
struct class *class,
struct device *start,
const struct device_type *type);
extern struct device *class_dev_iter_next(struct class_dev_iter *iter);
extern void class_dev_iter_exit(struct class_dev_iter *iter);


extern int class_for_each_device(struct class *class, struct device *start,
void *data,
int (*fn)(struct device *dev, void *data));
extern struct device *class_find_device(struct class *class,
struct device *start, void *data,
int (*match)(struct device *, void *));


struct class_attribute {
struct attribute attr;
ssize_t (*show)(struct class *class, struct class_attribute *attr,
char *buf);
ssize_t (*store)(struct class *class, struct class_attribute *attr,
const char *buf, size_t count);
};


#define CLASS_ATTR(_name, _mode, _show, _store) \
struct class_attribute class_attr_##_name = __ATTR(_name, _mode, _show, _store)


extern int __must_check class_create_file(struct class *class,
 const struct class_attribute *attr);
extern void class_remove_file(struct class *class,
     const struct class_attribute *attr);


/* Simple class attribute that is just a static string */


struct class_attribute_string {
struct class_attribute attr;
char *str;
};


/* Currently read-only only */
#define _CLASS_ATTR_STRING(_name, _mode, _str) \
{ __ATTR(_name, _mode, show_class_attr_string, NULL), _str }
#define CLASS_ATTR_STRING(_name, _mode, _str) \
struct class_attribute_string class_attr_##_name = \
_CLASS_ATTR_STRING(_name, _mode, _str)


extern ssize_t show_class_attr_string(struct class *class, struct class_attribute *attr,
                        char *buf);


struct class_interface {
struct list_head node;
struct class *class;


int (*add_dev) (struct device *, struct class_interface *);
void (*remove_dev) (struct device *, struct class_interface *);
};


extern int __must_check class_interface_register(struct class_interface *);
extern void class_interface_unregister(struct class_interface *);


extern struct class * __must_check __class_create(struct module *owner,
 const char *name,
 struct lock_class_key *key);
extern void class_destroy(struct class *cls);


/* This is a #define to keep the compiler from merging different
 * instances of the __key variable */
#define class_create(owner, name) \
({ \
static struct lock_class_key __key; \
__class_create(owner, name, &__key); \
})


/*
 * The type of device, "struct device" is embedded in. A class
 * or bus can contain devices of different types
 * like "partitions" and "disks", "mouse" and "event".
 * This identifies the device type and carries type-specific
 * information, equivalent to the kobj_type of a kobject.
 * If "name" is specified, the uevent will contain it in
 * the DEVTYPE variable.
 */
struct device_type {
const char *name;
const struct attribute_group **groups;
int (*uevent)(struct device *dev, struct kobj_uevent_env *env);
char *(*devnode)(struct device *dev, mode_t *mode);
void (*release)(struct device *dev);


const struct dev_pm_ops *pm;
};


/* interface for exporting device attributes */
struct device_attribute {
struct attribute attr;
ssize_t (*show)(struct device *dev, struct device_attribute *attr,
char *buf);
ssize_t (*store)(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count);
};


#define DEVICE_ATTR(_name, _mode, _show, _store) \
struct device_attribute dev_attr_##_name = __ATTR(_name, _mode, _show, _store)


extern int __must_check device_create_file(struct device *device,
const struct device_attribute *entry);
extern void device_remove_file(struct device *dev,
      const struct device_attribute *attr);
extern int __must_check device_create_bin_file(struct device *dev,
const struct bin_attribute *attr);
extern void device_remove_bin_file(struct device *dev,
  const struct bin_attribute *attr);
extern int device_schedule_callback_owner(struct device *dev,
void (*func)(struct device *dev), struct module *owner);


/* This is a macro to avoid include problems with THIS_MODULE */
#define device_schedule_callback(dev, func) \
device_schedule_callback_owner(dev, func, THIS_MODULE)


/* device resource management */
typedef void (*dr_release_t)(struct device *dev, void *res);
typedef int (*dr_match_t)(struct device *dev, void *res, void *match_data);


#ifdef CONFIG_DEBUG_DEVRES
extern void *__devres_alloc(dr_release_t release, size_t size, gfp_t gfp,
    const char *name);
#define devres_alloc(release, size, gfp) \
__devres_alloc(release, size, gfp, #release)
#else
extern void *devres_alloc(dr_release_t release, size_t size, gfp_t gfp);
#endif
extern void devres_free(void *res);
extern void devres_add(struct device *dev, void *res);
extern void *devres_find(struct device *dev, dr_release_t release,
dr_match_t match, void *match_data);
extern void *devres_get(struct device *dev, void *new_res,
dr_match_t match, void *match_data);
extern void *devres_remove(struct device *dev, dr_release_t release,
  dr_match_t match, void *match_data);
extern int devres_destroy(struct device *dev, dr_release_t release,
 dr_match_t match, void *match_data);


/* devres group */
extern void * __must_check devres_open_group(struct device *dev, void *id,
    gfp_t gfp);
extern void devres_close_group(struct device *dev, void *id);
extern void devres_remove_group(struct device *dev, void *id);
extern int devres_release_group(struct device *dev, void *id);


/* managed kzalloc/kfree for device drivers, no kmalloc, always use kzalloc */
extern void *devm_kzalloc(struct device *dev, size_t size, gfp_t gfp);
extern void devm_kfree(struct device *dev, void *p);


struct device_dma_parameters {
/*
* a low level driver may set these to teach IOMMU code about
* sg limitations.
*/
unsigned int max_segment_size;
unsigned long segment_boundary_mask;
};


struct device {
struct device *parent;


struct device_private *p;


struct kobject kobj;
const char *init_name; /* initial name of the device */
struct device_type *type;


struct mutex mutex; /* mutex to synchronize calls to
* its driver.
*/


struct bus_type *bus; /* type of bus device is on */
struct device_driver *driver; /* which driver has allocated this
  device */
void *platform_data; /* Platform specific data, device
  core doesn't touch it */
struct dev_pm_info power;


#ifdef CONFIG_NUMA
int numa_node; /* NUMA node this device is close to */
#endif
u64 *dma_mask; /* dma mask (if dma'able device) */
u64 coherent_dma_mask;/* Like dma_mask, but for
    alloc_coherent mappings as
    not all hardware supports
    64 bit addresses for consistent
    allocations such descriptors. */


struct device_dma_parameters *dma_parms;


struct list_head dma_pools; /* dma pools (if dma'ble) */


struct dma_coherent_mem *dma_mem; /* internal for coherent mem
    override */
/* arch specific additions */
struct dev_archdata archdata;
#ifdef CONFIG_OF
struct device_node *of_node;
#endif


dev_t devt; /* dev_t, creates the sysfs "dev" */


spinlock_t devres_lock;
struct list_head devres_head;


struct klist_node knode_class;
struct class *class;
const struct attribute_group **groups; /* optional groups */


void (*release)(struct device *dev);
};


/* Get the wakeup routines, which depend on struct device */
#include <linux/pm_wakeup.h>


static inline const char *dev_name(const struct device *dev)
{
/* Use the init name until the kobject becomes available */
if (dev->init_name)
return dev->init_name;


return kobject_name(&dev->kobj);
}


extern int dev_set_name(struct device *dev, const char *name, ...)
__attribute__((format(printf, 2, 3)));


#ifdef CONFIG_NUMA
static inline int dev_to_node(struct device *dev)
{
return dev->numa_node;
}
static inline void set_dev_node(struct device *dev, int node)
{
dev->numa_node = node;
}
#else
static inline int dev_to_node(struct device *dev)
{
return -1;
}
static inline void set_dev_node(struct device *dev, int node)
{
}
#endif


static inline unsigned int dev_get_uevent_suppress(const struct device *dev)
{
return dev->kobj.uevent_suppress;
}


static inline void dev_set_uevent_suppress(struct device *dev, int val)
{
dev->kobj.uevent_suppress = val;
}


static inline int device_is_registered(struct device *dev)
{
return dev->kobj.state_in_sysfs;
}


static inline void device_enable_async_suspend(struct device *dev)
{
if (!dev->power.in_suspend)
dev->power.async_suspend = true;
}


static inline void device_disable_async_suspend(struct device *dev)
{
if (!dev->power.in_suspend)
dev->power.async_suspend = false;
}


static inline bool device_async_suspend_enabled(struct device *dev)
{
return !!dev->power.async_suspend;
}


static inline void device_lock(struct device *dev)
{
mutex_lock(&dev->mutex);
}


static inline int device_trylock(struct device *dev)
{
return mutex_trylock(&dev->mutex);
}


static inline void device_unlock(struct device *dev)
{
mutex_unlock(&dev->mutex);
}


void driver_init(void);


/*
 * High level routines for use by the bus drivers
 */
extern int __must_check device_register(struct device *dev);
extern void device_unregister(struct device *dev);
extern void device_initialize(struct device *dev);
extern int __must_check device_add(struct device *dev);
extern void device_del(struct device *dev);
extern int device_for_each_child(struct device *dev, void *data,
    int (*fn)(struct device *dev, void *data));
extern struct device *device_find_child(struct device *dev, void *data,
int (*match)(struct device *dev, void *data));
extern int device_rename(struct device *dev, const char *new_name);
extern int device_move(struct device *dev, struct device *new_parent,
      enum dpm_order dpm_order);
extern const char *device_get_devnode(struct device *dev,
     mode_t *mode, const char **tmp);
extern void *dev_get_drvdata(const struct device *dev);
extern void dev_set_drvdata(struct device *dev, void *data);


/*
 * Root device objects for grouping under /sys/devices
 */
extern struct device *__root_device_register(const char *name,
    struct module *owner);
static inline struct device *root_device_register(const char *name)
{
return __root_device_register(name, THIS_MODULE);
}
extern void root_device_unregister(struct device *root);


static inline void *dev_get_platdata(const struct device *dev)
{
return dev->platform_data;
}


/*
 * Manual binding of a device to driver. See drivers/base/bus.c
 * for information on use.
 */
extern int __must_check device_bind_driver(struct device *dev);
extern void device_release_driver(struct device *dev);
extern int  __must_check device_attach(struct device *dev);
extern int __must_check driver_attach(struct device_driver *drv);
extern int __must_check device_reprobe(struct device *dev);


/*
 * Easy functions for dynamically creating devices on the fly
 */
extern struct device *device_create_vargs(struct class *cls,
 struct device *parent,
 dev_t devt,
 void *drvdata,
 const char *fmt,
 va_list vargs);
extern struct device *device_create(struct class *cls, struct device *parent,
   dev_t devt, void *drvdata,
   const char *fmt, ...)
   __attribute__((format(printf, 5, 6)));
extern void device_destroy(struct class *cls, dev_t devt);


/*
 * Platform "fixup" functions - allow the platform to have their say
 * about devices and actions that the general device layer doesn't
 * know about.
 */
/* Notify platform of device discovery */
extern int (*platform_notify)(struct device *dev);


extern int (*platform_notify_remove)(struct device *dev);




/**
 * get_device - atomically increment the reference count for the device.
 *
 */
extern struct device *get_device(struct device *dev);
extern void put_device(struct device *dev);


extern void wait_for_device_probe(void);


#ifdef CONFIG_DEVTMPFS
extern int devtmpfs_create_node(struct device *dev);
extern int devtmpfs_delete_node(struct device *dev);
extern int devtmpfs_mount(const char *mntdir);
#else
static inline int devtmpfs_create_node(struct device *dev) { return 0; }
static inline int devtmpfs_delete_node(struct device *dev) { return 0; }
static inline int devtmpfs_mount(const char *mountpoint) { return 0; }
#endif


/* drivers/base/power/shutdown.c */
extern void device_shutdown(void);


/* drivers/base/sys.c */
extern void sysdev_shutdown(void);


/* debugging and troubleshooting/diagnostic helpers. */
extern const char *dev_driver_string(const struct device *dev);




#ifdef CONFIG_PRINTK


extern int dev_printk(const char *level, const struct device *dev,
     const char *fmt, ...)
__attribute__ ((format (printf, 3, 4)));
extern int dev_emerg(const struct device *dev, const char *fmt, ...)
__attribute__ ((format (printf, 2, 3)));
extern int dev_alert(const struct device *dev, const char *fmt, ...)
__attribute__ ((format (printf, 2, 3)));
extern int dev_crit(const struct device *dev, const char *fmt, ...)
__attribute__ ((format (printf, 2, 3)));
extern int dev_err(const struct device *dev, const char *fmt, ...)
__attribute__ ((format (printf, 2, 3)));
extern int dev_warn(const struct device *dev, const char *fmt, ...)
__attribute__ ((format (printf, 2, 3)));
extern int dev_notice(const struct device *dev, const char *fmt, ...)
__attribute__ ((format (printf, 2, 3)));
extern int _dev_info(const struct device *dev, const char *fmt, ...)
__attribute__ ((format (printf, 2, 3)));


#else


static inline int dev_printk(const char *level, const struct device *dev,
     const char *fmt, ...)
__attribute__ ((format (printf, 3, 4)));
static inline int dev_printk(const char *level, const struct device *dev,
     const char *fmt, ...)
{ return 0; }


static inline int dev_emerg(const struct device *dev, const char *fmt, ...)
__attribute__ ((format (printf, 2, 3)));
static inline int dev_emerg(const struct device *dev, const char *fmt, ...)
{ return 0; }
static inline int dev_crit(const struct device *dev, const char *fmt, ...)
__attribute__ ((format (printf, 2, 3)));
static inline int dev_crit(const struct device *dev, const char *fmt, ...)
{ return 0; }
static inline int dev_alert(const struct device *dev, const char *fmt, ...)
__attribute__ ((format (printf, 2, 3)));
static inline int dev_alert(const struct device *dev, const char *fmt, ...)
{ return 0; }
static inline int dev_err(const struct device *dev, const char *fmt, ...)
__attribute__ ((format (printf, 2, 3)));
static inline int dev_err(const struct device *dev, const char *fmt, ...)
{ return 0; }
static inline int dev_warn(const struct device *dev, const char *fmt, ...)
__attribute__ ((format (printf, 2, 3)));
static inline int dev_warn(const struct device *dev, const char *fmt, ...)
{ return 0; }
static inline int dev_notice(const struct device *dev, const char *fmt, ...)
__attribute__ ((format (printf, 2, 3)));
static inline int dev_notice(const struct device *dev, const char *fmt, ...)
{ return 0; }
static inline int _dev_info(const struct device *dev, const char *fmt, ...)
__attribute__ ((format (printf, 2, 3)));
static inline int _dev_info(const struct device *dev, const char *fmt, ...)
{ return 0; }


#endif


/*
 * Stupid hackaround for existing uses of non-printk uses dev_info
 *
 * Note that the definition of dev_info below is actually _dev_info
 * and a macro is used to avoid redefining dev_info
 */


#define dev_info(dev, fmt, arg...) _dev_info(dev, fmt, ##arg)


#if defined(DEBUG)
#define dev_dbg(dev, format, arg...) \
dev_printk(KERN_DEBUG, dev, format, ##arg)
#elif defined(CONFIG_DYNAMIC_DEBUG)
#define dev_dbg(dev, format, ...)     \
do {     \
dynamic_dev_dbg(dev, format, ##__VA_ARGS__); \
} while (0)
#else
#define dev_dbg(dev, format, arg...) \
({ \
if (0) \
dev_printk(KERN_DEBUG, dev, format, ##arg); \
0; \
})
#endif


#ifdef VERBOSE_DEBUG
#define dev_vdbg dev_dbg
#else
#define dev_vdbg(dev, format, arg...) \
({ \
if (0) \
dev_printk(KERN_DEBUG, dev, format, ##arg); \
0; \
})
#endif


/*
 * dev_WARN() acts like dev_printk(), but with the key difference
 * of using a WARN/WARN_ON to get the message out, including the
 * file/line information and a backtrace.
 */
#define dev_WARN(dev, format, arg...) \
WARN(1, "Device: %s\n" format, dev_driver_string(dev), ## arg);


/* Create alias, so I can be autoloaded. */
#define MODULE_ALIAS_CHARDEV(major,minor) \
MODULE_ALIAS("char-major-" __stringify(major) "-" __stringify(minor))
#define MODULE_ALIAS_CHARDEV_MAJOR(major) \
MODULE_ALIAS("char-major-" __stringify(major) "-*")


#ifdef CONFIG_SYSFS_DEPRECATED
extern long sysfs_deprecated;
#else
#define sysfs_deprecated 0
#endif


#endif /* _DEVICE_H_ */

<think>我们正在解决在Ubuntu下使用arm-linux-gnueabihf-gcc交叉编译时出现的链接错误:找不到paho-mqtt、curl、crypto库。错误信息为:`cannot find -lpaho-mqtt3c -lcurl -lcrypto`。 根据引用[1]中的信息,我们知道这些库都是开发库,在交叉编译环境下,我们需要确保已经为交叉编译目标(arm-linux-gnueabihf)安装了相应的开发库,或者已经手动编译并正确安装了这些库的交叉编译版本。 引用[2]提供了一个Makefile的示例,其中在交叉编译时指定了头文件路径和库路径(通过`CFLAGS`和`LFLAGS`)。我们可以参考这个思路,在交叉编译时指定库的路径。 解决方法如下: 1. **确认交叉编译工具链已安装** 确保已经安装了arm-linux-gnueabihf工具链: ```bash sudo apt update sudo apt install gcc-arm-linux-gnueabihf g++-arm-linux-gnueabihf ``` 2. **安装或编译目标平台的库** - 对于curl和crypto(openssl),我们可以尝试安装Ubuntu提供的armhf架构的预编译库: ```bash sudo apt install libcurl4-openssl-dev:armhf libssl-dev:armhf ``` 注意:如果系统提示找不到这些包,可能需要启用多架构支持并更新: ```bash sudo dpkg --add-architecture armhf sudo apt update sudo apt install libcurl4-openssl-dev:armhf libssl-dev:armhf ``` - 对于paho-mqtt,Ubuntu官方仓库可能没有提供armhf的预编译包,因此需要从源代码交叉编译。 3. **交叉编译paho-mqtt库** 如果paho-mqtt库没有预编译包,我们需要下载源代码并交叉编译: ```bash # 下载源代码 git clone https://github.com/eclipse/paho.mqtt.c.git cd paho.mqtt.c mkdir build.armhf cd build.armhf # 使用CMake进行交叉编译 cmake .. -DCMAKE_C_COMPILER=arm-linux-gnueabihf-gcc -DCMAKE_INSTALL_PREFIX=/usr/arm-linux-gnueabihf make sudo make install ``` 注意:这里我们将安装前缀设置为`/usr/arm-linux-gnueabihf`,这样交叉编译器会自动在该路径下查找库和头文件。 4. **在编译时指定库路径** 如果库安装到了非标准路径,需要在编译时通过`-L`选项指定库的路径,通过`-I`选项指定头文件路径。例如,假设我们将paho-mqtt库安装到了`/path/to/armhf-libs`,则编译命令应类似: ```bash arm-linux-gnueabihf-gcc -o output your_program.c -I/path/to/armhf-libs/include -L/path/to/armhf-libs/lib -lpaho-mqtt3c -lcurl -lcrypto ``` 5. **检查库的架构** 使用`file`命令检查库文件是否确实是ARM架构的: ```bash file /path/to/armhf-libs/lib/libpaho-mqtt3c.so ``` 应该输出类似:`ELF 32-bit LSB shared object, ARM, ...` 6. **使用pkg-config(如果库支持)** 如果交叉编译的库安装了pkg-config的`.pc`文件,我们可以使用: ```bash export PKG_CONFIG_PATH=/path/to/armhf-libs/lib/pkgconfig arm-linux-gnueabihf-gcc -o output your_program.c $(pkg-config --cflags --libs libcurl libssl libpaho-mqtt3c) ``` 7. **设置环境变量** 为了方便,可以将库路径添加到环境变量中: ```bash export LIBRARY_PATH=/path/to/armhf-libs/lib:$LIBRARY_PATH export C_INCLUDE_PATH=/path/to/armhf-libs/include:$C_INCLUDE_PATH ``` 8. **检查链接器配置** 确保链接器能够找到这些库。可以创建一个链接器脚本或在命令行中指定。 如果按照上述步骤操作后仍然出现链接错误,请检查库文件名是否正确(比如libpaho-mqtt3c.so是否存在),以及库文件是否在指定的路径中。 注意:交叉编译时,所有依赖的库都必须是为目标平台(armhf)编译的。不能使用主机(x86_64)的库。 如果问题仍然存在,请提供更多关于你的编译环境和步骤的信息。 §§ 相关问题 §§ 1. 如何在Ubuntu中启用多架构支持? 2. 如何为交叉编译创建CMake工具链文件? 3. 如何检查动态库的依赖项(交叉编译环境)? 4. 交叉编译时如何设置静态链接?</think>### 解决 Ubuntu 下交叉编译链接错误:找不到 paho-mqtt、curl、crypto 库 当使用 `arm-linux-gnueabihf-gcc` 进行交叉编译时出现 `cannot find -lpaho-mqtt3c -lcurl -lcrypto` 错误,表明交叉编译工具链无法找到目标平台(ARM)的开发库。以下是系统化的解决方案: --- #### 🔧 核心解决步骤 1. **安装目标平台的开发库** 通过多架构支持安装 ARM 版本的库: ```bash sudo dpkg --add-architecture armhf # 启用 ARM 架构支持 sudo apt update sudo apt install \ libpaho-mqtt-dev:armhf \ libcurl4-openssl-dev:armhf \ libssl-dev:armhf # 安装 ARM 版本的开发库[^1] ``` 2. **验证库文件位置** 检查 ARM 库是否已正确安装: ```bash # 检查库文件路径 ls /usr/arm-linux-gnueabihf/lib/libpaho-mqtt3c* ls /usr/arm-linux-gnueabihf/lib/libcurl* ls /usr/arm-linux-gnueabihf/lib/libcrypto* ``` 3. **在编译命令中指定库路径** 修改 Makefile 或编译命令,明确指向 ARM 库: ```makefile # 修改 Makefile 示例(参考引用[2]) CC = arm-linux-gnueabihf-gcc CFLAGS += -I/usr/arm-linux-gnueabihf/include LDFLAGS += -L/usr/arm-linux-gnueabihf/lib -lpaho-mqtt3c -lcurl -lcrypto ``` 4. **手动编译缺失库(若无预编译包)** 以 paho-mqtt 为例的交叉编译流程: ```bash # 下载源码 git clone https://github.com/eclipse/paho.mqtt.c cd paho.mqtt.c # 创建构建目录 mkdir build.arm && cd build.arm # 配置交叉编译 cmake .. -DCMAKE_C_COMPILER=arm-linux-gnueabihf-gcc \ -DCMAKE_INSTALL_PREFIX=/usr/arm-linux-gnueabihf make && sudo make install # 编译并安装到工具链目录 ``` --- #### ⚠️ 关键注意事项 1. **架构匹配原则** - 主机(x86_64)库 ≠ 目标(ARM)库 - 必须使用 `:armhf` 后缀安装目标平台专用包 2. **工具链完整性检查** ```bash # 验证工具链配置 arm-linux-gnueabihf-gcc -print-sysroot # 应输出类似: /usr/arm-linux-gnueabihf # 检查链接器搜索路径 arm-linux-gnueabihf-gcc -Xlinker --verbose 2>/dev/null | grep SEARCH_DIR ``` 3. **符号链接修复** 若存在库版本不匹配: ```bash cd /usr/arm-linux-gnueabihf/lib sudo ln -s libpaho-mqtt3c.so.1 libpaho-mqtt3c.so # 创建符号链接 ``` --- #### 🔍 验证解决方案 创建测试文件 `test_link.c`: ```c #include <paho_mqtt_c/MQTTClient.h> #include <curl/curl.h> #include <openssl/ssl.h> int main() { MQTTClient client; CURL *curl = curl_easy_init(); SSL_CTX *ctx = SSL_CTX_new(TLS_method()); return 0; } ``` 编译验证: ```bash arm-linux-gnueabihf-gcc test_link.c \ -I/usr/arm-linux-gnueabihf/include \ -L/usr/arm-linux-gnueabihf/lib \ -lpaho-mqtt3c -lcurl -lcrypto -o arm_test ``` **成功标志**:生成可执行的 `arm_test` 文件 --- #### 📚 技术原理 交叉编译链接错误的根本原因是**工具链搜索路径不匹配**: 1. 主机库路径:`/usr/lib/x86_64-linux-gnu/` 2. ARM 库路径:`/usr/arm-linux-gnueabihf/lib/` 3. 编译器默认搜索主机路径,需通过 `-L` 显式指定目标路径[^2] ---
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