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Usb driver programming, ioctl returns -1

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http://www.linuxquestions.org – I'm creating a usb device driver that needs to be able to read from two different endpoints. I couldn't see any way of having two read functions in the driver, so I got round this by reading from one of the endpoints with read, and the other with ioctl. However this hasn't worked, the ioctl call from c returns -1. I added a printk command in the driver in the ioctl function, however looking at kern.log I can see that this function is never being called. Just to mention, debugging is enabled, the other drivers work fine and the ioctl function has been added to the fil (HowTos)

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Submitted by robot1 on 07/22/2010 – Made popular on 07/22/2010

Stories similar to Usb driver programming, ioctl returns -1

I would like to call a ioctl function from a program launched with a low-privilege user. Is it possible and, if so, how should i perform this ? Here is my ioctl action :

def get_ip_address(ifname): s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

I have mapped the pci memory in user space like

fs = open("/dev/mem",O_RDWR | O_SYNC);

mmap_src = mmap(NULL, BUFF_COUNT, PROT_READ | PROT_WRITE, MAP_SHARED, fs, 0xe0000000);

0xe0000000 is the addressof pci memory device.

I am making ioctl calls for setting address to an existing network device.The ioctl calls fails with error 13 permission denied. The ioctl calls is made by native library which is used by android application.The application runs in user mode.

I tried to run my application in system process by changing android.shareduserid ="android.uid.system" but still ioctl call fails.

Please suggest the way t

lsmod , /proc/modules and slabinfo , /proc/meminfo does NOT give how much memory my kernel module is using

is there a way to find this out ?

btw, I wrote a small test program basically, a device driver that takes ioctl call to alloc 1MB and I send this ioctl message every second from my application so my drive does kmalloc every second.

I have developed a driver for a PCI Express card which we also developed. The driver allocates a 16kB DMA buffer using pci_alloc_consistent() which the user space application will mmap().

The problem is the virtual address returned by mmap() in user space cannot seem to access the memory buffer. I test it by writing a known value to the user virtual address.

I am just confused like how can I break cmd=3222823425 value into different parts to figure out what this command means actually in the Linux kernel.

I am just confused like how can I break cmd=3222823425 value into different parts to figure out what this command means actually in the Linux kernel.

I have written one kernel module which implements hooking of system calls. In the hooked system call, I just printk input parameters passed to that function and in case of ioctl, I get

fd=21, cmd=3222823425 and arg=3198662648

After decoding, I get to know that it's mmap2 system call being made through ioctl.

And in syscalls.h file, there is unmap sys call but not mmap.

First of all, is it possible to call ioctl from a kernel module? Can anyone provide an example of how it's used?