Question

我需要使用ioctl测试一个usbfs设备。我需要使用ioctl(fd, USBDEVFS_REAPURBNDELAY, &receive);。但是USBDEVFS_REAPURBNDELAY是在内核头中定义的，所以我包含了一些像这样的内核文件：

#include <linux/usb.h>
#include <linux/usbdevice_fs.h>
#include <asm/byteorder.h>
#include <linux/usb/ch9.h>

并使用gcc -g -I /usr/src/linux-3.4.4-2-pae/include/ -o /home/madper/kernel/usb/select_for_usb /home/madper/kernel/usb/select_for_usb.c

进行编译

它说#warning "Attempt to use kernel headers from user space, see http://kernelnewbies.org/KernelHeaders" [-Wcpp]

并且有很多错误，所以，使用内核头文件的正确方法是什么？

/usr/src/linux-3.4.4-2-pae/include/linux/mod_devicetable.h:21:2: error: unknown type name ‘kernel_ulong_t’
/usr/src/linux-3.4.4-2-pae/include/linux/mod_devicetable.h:36:2: error: unknown type name ‘kernel_ulong_t’
/usr/src/linux-3.4.4-2-pae/include/linux/mod_devicetable.h:37:33: error: ‘kernel_ulong_t’ undeclared here (not in a function)
/usr/src/linux-3.4.4-2-pae/include/linux/mod_devicetable.h:37:3: error: requested alignment is not an integer constant
/usr/src/linux-3.4.4-2-pae/include/linux/mod_devicetable.h:119:2: error: expected specifier-qualifier-list before ‘kernel_ulong_t’
/usr/src/linux-3.4.4-2-pae/include/linux/mod_devicetable.h:141:2: error: expected specifier-qualifier-list before ‘kernel_ulong_t’
/usr/src/linux-3.4.4-2-pae/include/linux/mod_devicetable.h:154:2: error: expected specifier-qualifier-list before ‘kernel_ulong_t’
/usr/src/linux-3.4.4-2-pae/include/linux/mod_devicetable.h:168:2: error: expected specifier-qualifier-list before ‘kernel_ulong_t’
/usr/src/linux-3.4.4-2-pae/include/linux/mod_devicetable.h:179:2: error: expected specifier-qualifier-list before ‘kernel_ulong_t’
/usr/src/linux-3.4.4-2-pae/include/linux/mod_devicetable.h:187:2: error: expected specifier-qualifier-list before ‘kernel_ulong_t’
/usr/src/linux-3.4.4-2-pae/include/linux/mod_devicetable.h:195:2: error: expected specifier-qualifier-list before ‘kernel_ulong_t’
/usr/src/linux-3.4.4-2-pae/include/linux/mod_devicetable.h:200:2: error: expected specifier-qualifier-list before ‘kernel_ulong_t’
/usr/src/linux-3.4.4-2-pae/include/linux/mod_devicetable.h:227:2: error: expected specifier-qualifier-list before ‘kernel_ulong_t’
/usr/src/linux-3.4.4-2-pae/include/linux/mod_devicetable.h:260:2: error: expected specifier-qualifier-list before ‘kernel_ulong_t’
/usr/src/linux-3.4.4-2-pae/include/linux/mod_devicetable.h:314:2: error: expected specifier-qualifier-list before ‘kernel_ulong_t’
/usr/src/linux-3.4.4-2-pae/include/linux/mod_devicetable.h:341:2: error: expected specifier-qualifier-list before ‘kernel_ulong_t’
/usr/src/linux-3.4.4-2-pae/include/linux/mod_devicetable.h:366:2: error: expected specifier-qualifier-list before ‘kernel_ulong_t’
/usr/src/linux-3.4.4-2-pae/include/linux/mod_devicetable.h:413:2: error: expected specifier-qualifier-list before ‘kernel_ulong_t’
/usr/src/linux-3.4.4-2-pae/include/linux/mod_devicetable.h:433:2: error: expected specifier-qualifier-list before ‘kernel_ulong_t’
/usr/src/linux-3.4.4-2-pae/include/linux/mod_devicetable.h:444:2: error: expected specifier-qualifier-list before ‘kernel_ulong_t’
/usr/src/linux-3.4.4-2-pae/include/linux/mod_devicetable.h:479:2: error: expected specifier-qualifier-list before ‘kernel_ulong_t’
/usr/src/linux-3.4.4-2-pae/include/linux/mod_devicetable.h:508:2: error: expected specifier-qualifier-list before ‘kernel_ulong_t’
/usr/src/linux-3.4.4-2-pae/include/linux/mod_devicetable.h:540:2: error: expected specifier-qualifier-list before ‘kernel_ulong_t’
/usr/src/linux-3.4.4-2-pae/include/linux/mod_devicetable.h:551:2: error: expected specifier-qualifier-list before ‘kernel_ulong_t’
/usr/src/linux-3.4.4-2-pae/include/linux/mod_devicetable.h:566:2: error: expected specifier-qualifier-list before ‘kernel_ulong_t’
/usr/src/linux-3.4.4-2-pae/include/linux/mod_devicetable.h:582:2: error: expected specifier-qualifier-list before ‘kernel_ulong_t’
/home/madper/kernel/usb/select_for_usb.c: In function ‘main’:
/home/madper/kernel/usb/select_for_usb.c:46:30: error: expected expression before ‘void’

Answer 1

你真的不应该直接包含内核头文件。在某些情况下，这是必要的，并且可能最好的方法是获取内核头文件的副本并仅删除所需的部分。但在这种情况下，我不确定我理解为什么需要内核头文件。为什么仅包含<linux/usbdevice_fs.h>？

不起作用

在我查看的所有系统（几个不同的Ubuntu系统和一个RHEL 6系统）上，该文件可以包含在用户空间中，并且具有USBDEVFS_REAPURBNDELAY的定义。我试过了

#include <stdio.h>
#include <sys/ioctl.h>
#include <linux/usbdevice_fs.h>

int main()
{
    printf("USBDEVFS_REAPURBNDELAY is %ld\n", USBDEVFS_REAPURBNDELAY);
    return 0;
}

我可以干净利落地构建它，当我运行它时，我得到了

USBDEVFS_REAPURBNDELAY is 1074287885

所以至少根据你上面写的内容，你不需要任何ioctl定义的内核头文件。我怀疑你认为你需要的任何其他用户空间USB内容同样会以干净的标题导出到用户空间。

Answer 2

您不能将内核头文件用于用户程序。即使你通过某种方式做到这一点，也强烈劝阻。请查看以下链接以获得更多说明。

http://lwn.net/Articles/113349/

如果你想从用户空间控制USB设备，请查看libusb。

如何使用内核头文件编译用户空间程序

2 个答案: