编译Linux v5.4.0内核模块时出现eth_hw_addr_set隐式声明错误

环境信息 #

• 系统：Ubuntu Server 20.04.6
• 已安装依赖：gcc、make、linux-headers-5.4.0-150-generic
• 内核版本：uname -r 输出 5.4.0-150-generic，内核头文件版本匹配
• 编译目标：infinitv_pcie项目的内核模块

编译错误信息 #

/home/robert/ceton-drivers/infinitv_pcie-master/ctn91xx_net.c: In function ‘ctn91xx_net_init’:
/home/robert/ceton-drivers/infinitv_pcie-master/ctn91xx_net.c:84:5: error: implicit declaration of function ‘eth_hw_addr_set’; did you mean ‘eth_addr_dec’? [-Werror=implicit-function-declaration]
   84 |     eth_hw_addr_set(netdev,addr);
      |     ^~~~~~~~~~~~~~~
      |     eth_addr_dec

出错函数源代码 #

int ctn91xx_net_init(ctn91xx_dev_t* dev)
{
    struct net_device *netdev = NULL;
    ctn91xx_net_priv_t *priv = NULL;
    u8 addr[6];
    int i;

    netdev = alloc_etherdev(sizeof(ctn91xx_net_priv_t));

    if (netdev == NULL) {
        ERROR("unable to alloc new ethernet");
        return -ENOMEM;
    }

#if USE_PCI
    SET_NETDEV_DEV(netdev, &dev->pdev->dev);
#endif

    priv = netdev_priv(netdev);
    priv->ctn91xx_dev = dev;
    spin_lock_init(&priv->lock);

    snprintf(netdev->name, 20, "ctn%d", dev->board_number);

#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,29)
    netdev->netdev_ops = &ctn91xx_net_device_ops;
#else
    netdev->open = ctn91xx_net_open;
    netdev->hard_start_xmit = ctn91xx_net_start_xmit;
    netdev->stop = ctn91xx_net_stop;
    netdev->get_stats = ctn91xx_net_get_stats;
    netdev->tx_timeout = ctn91xx_net_tx_timeout;
#endif
    netdev->watchdog_timeo = CTN91XX_NET_TX_TIMEOUT;

    i = register_netdev(netdev);
    if (i) {
        ERROR("failed to register netdev");
        free_netdev(netdev);
        return -EINVAL;
    }

#if USE_PCI
    addr[0] = 0x00;
    addr[1] = 0x22;
    addr[2] = 0x2c;
    addr[3] = 0xff;
    addr[4] = 0xff;
    addr[5] = 0xff - dev->board_number;
    eth_hw_addr_set(netdev,addr);
#else
    random_ether_addr(netdev->dev_addr);
#endif

    netdev->irq = dev->irq;
    netdev->base_addr = (unsigned long)dev->hw_reg_base;

    dev->net_dev = netdev;

#if USE_PCI
    ctn91xx_write8(1, dev->msg_base, MSG_BUFFER_INT_ENABLE);
#endif

    return 0;
}

解决方法 #

方法1：添加必要的头文件 #

eth_hw_addr_set函数定义在<linux/etherdevice.h>中，检查ctn91xx_net.c文件顶部是否包含该头文件，如果没有，添加：

#include <linux/etherdevice.h>

方法2：替换为内核兼容的写法 #

如果添加头文件后仍报错，说明Ubuntu 20.04的5.4内核版本不支持eth_hw_addr_set函数，可以直接将MAC地址复制到网卡设备的dev_addr字段，替换原有代码：
把

eth_hw_addr_set(netdev,addr);

替换为：

memcpy(netdev->dev_addr, addr, ETH_ALEN);

如果代码中没有包含<linux/string.h>（memcpy的头文件），需要在文件顶部添加：

#include <linux/string.h>

内容的提问来源于stack exchange，提问作者Robert Rathbone