open() 返回“没有这样的设备” 错误，但是有这样的设备（linux）
我正在尝试使用有点旧的 DAQ，并且必须跳过一些步骤才能获得旧的（大约 2004 年）设备驱动程序以进行编译（DTI-DT340 Linux-DAQ-PCI）。
我已经完成了编译，我可以加载内核模块，它找到卡，并且我可以使用 mknod 创建字符设备。
但我似乎无法打开这些设备，并且当我尝试打开时不断收到errno 19 (ENODEV)“没有这样的设备”，
open("/dev/dt340/0",O_RDWR);
但 mknod 没有抱怨制作它，而且它就在那里：
# ls -l /dev/dt340/
total 0
crw-rw-r-- 1 root staff 250, 0 2009-04-23 11:02 0
crw-rw-r-- 1 root staff 250, 1 2009-04-23 11:02 1
crw-rw-r-- 1 root staff 250, 2 2009-04-23 11:02 2
crw-rw-r-- 1 root staff 250, 3 2009-04-23 11:02 3
有什么东西吗？我疏忽了做什么？ 打开失败的原因可能是什么？
这是我用来加载驱动程序和创建设备的脚本。
#!/bin/bash
module="dt340"
device="dt340"
mode="664"
# invoke modprobe with all arguments we were passed
#/sbin/modprobe -t misc -lroot -f -s $module.o $* || exit 1
insmod $module.ko
# remove stale nodes
rm -f /dev/${device}/[0-3]
major=`awk "\\$2==\"$module\" {print \\$1}" /proc/devices`
mkdir -p /dev/${device}
mknod /dev/${device}/0 c $major 0
mknod /dev/${device}/1 c $major 1
mknod /dev/${device}/2 c $major 2
mknod /dev/${device}/3 c $major 3
# give appropriate group/permissions, and change the group
# not all distributions have staff; some have "users" instead
group="staff"
grep '^staff:' /etc/group > /dev/null || group="users"
chgrp $group /dev/${device}/[0-3]
chmod $mode /dev/${device}/[0-3]
一些附加信息：
#grep dt340 /proc/devices
250 dt340
# lsmod | grep dt340
dt340 21516 0
# tail /var/log/messages
Apr 23 11:59:26 ve kernel: [ 412.862139] dt340 0000:03:01.0: PCI INT A -> GSI 22 (level, low) -> IRQ 22
Apr 23 11:59:26 ve kernel: [ 412.862362] dt340: In function dt340_init_one:
Apr 23 11:59:26 ve kernel: [ 412.862363] Device DT340 Rev 0x0 detected at address 0xfebf0000
#lspci | grep 340
03:01.0 Multimedia controller: Data Translation DT340
解答： printk 确认 -ENODEV 是从 open() 内部抛出的。 遵循旧式
while ((pdev = pci_find_device(PCI_VENDOR_ID_DTI, PCI_ANY_ID, pdev)))
（已弃用），if(!pdev) 最终为 true，并返回 -ENODEV。
我正在一点点接近 - 我想我必须完成并更新 pci 代码以使用更现代的机制......
I'm trying to use a somewhat old DAQ, and had to jump through a few hoops to get an old (circa 2004) device driver for it to compile (DTI-DT340 Linux-DAQ-PCI).
I've gotten to the point where it compiles, I can load the kernel module, it finds the card, and I can create the character devices using mknod.
But I can't seem to open these devices and keep getting errno 19 (ENODEV) 'No such device' when I try to
open("/dev/dt340/0",O_RDWR);
but mknod had no complaints about making it, and it's there:
# ls -l /dev/dt340/
total 0
crw-rw-r-- 1 root staff 250, 0 2009-04-23 11:02 0
crw-rw-r-- 1 root staff 250, 1 2009-04-23 11:02 1
crw-rw-r-- 1 root staff 250, 2 2009-04-23 11:02 2
crw-rw-r-- 1 root staff 250, 3 2009-04-23 11:02 3
Is there something I'm neglecting to do? What might be a reason open fails?
Here's the script I use to load the driver and make the devices.
#!/bin/bash
module="dt340"
device="dt340"
mode="664"
# invoke modprobe with all arguments we were passed
#/sbin/modprobe -t misc -lroot -f -s $module.o $* || exit 1
insmod $module.ko
# remove stale nodes
rm -f /dev/${device}/[0-3]
major=`awk "\\$2==\"$module\" {print \\$1}" /proc/devices`
mkdir -p /dev/${device}
mknod /dev/${device}/0 c $major 0
mknod /dev/${device}/1 c $major 1
mknod /dev/${device}/2 c $major 2
mknod /dev/${device}/3 c $major 3
# give appropriate group/permissions, and change the group
# not all distributions have staff; some have "users" instead
group="staff"
grep '^staff:' /etc/group > /dev/null || group="users"
chgrp $group /dev/${device}/[0-3]
chmod $mode /dev/${device}/[0-3]
Some additional info:
#grep dt340 /proc/devices
250 dt340
# lsmod | grep dt340
dt340 21516 0
# tail /var/log/messages
Apr 23 11:59:26 ve kernel: [ 412.862139] dt340 0000:03:01.0: PCI INT A -> GSI 22 (level, low) -> IRQ 22
Apr 23 11:59:26 ve kernel: [ 412.862362] dt340: In function dt340_init_one:
Apr 23 11:59:26 ve kernel: [ 412.862363] Device DT340 Rev 0x0 detected at address 0xfebf0000
#lspci | grep 340
03:01.0 Multimedia controller: Data Translation DT340
ANSWER: A printk confirmed that the -ENODEV was thrown from inside open(). Following an oldstyle
while ((pdev = pci_find_device(PCI_VENDOR_ID_DTI, PCI_ANY_ID, pdev)))
(which is deprecated), if(!pdev) ends up true, and returns the -ENODEV.
I'm inching closer - I guess I have to work through and update the pci code to use more modern mechanisms...
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如果设备显示在 /proc/devices 中，并且您确定 mknod 中的编号正确，则驱动程序本身会拒绝打开。 驱动程序可以从 open() 返回任何错误代码 - 包括“没有这样的设备”，如果发现初始化硬件出现问题，则可能会出现这种情况。
If the device shows up in /proc/devices, and you're sure you've got the number right in mknod, then the driver itself is refusing the open. The driver can return any error code from open() - including "no such device", which it might if it discovered a problem initialising the hardware.
估计是驱动的问题，检查一下open函数。
它显示在 /proc/devices 中，因此所有通用设备的内容似乎都可以。
I'd guess it is a problem in the driver, check the open function.
It shows up in /proc/devices, so all the generic device stuff seems to be ok.
mknod 不关心是否存在与给定的主/次编号对应的设备。 您确定 insmod 正在安装您的模块吗？ lsmod 告诉你什么？
我不熟悉必须添加“.ko”扩展名。 这是您的设备驱动程序特有的吗？
mknod doesn't care if there is an device corresponding to the given major/minor numbers. Are you sure insmod is installing your module? What does lsmod tell you?
I'm unfamiliar with having to add the ".ko" extension. Is that something specific to your device driver?
通过 lspci 检查并确保硬件已正确初始化。 如果您的系统支持热插拔，pci_find_device 将不起作用。 这个问题是一个refcnt。 最好的处理和学习方法是剖析 API。 博尔！！
Check through lspci and make sure hardware is properly initialized. If your system supports hotplug, pci_find_device won't work. The problem with this is a refcnt. The best way to deal and learn is to dissect the API. BOL !!