All, I am working on porting 32-bit application code to run over a 64-bit kernel. The 32 bit code calls socket ioctl to programs some registers in the driver (e1000) and then opens a raw socket. The struct ifreq is used to construct the command as expected. The problem i am facing is that, the data which is copied back into the ioctl buffer is not visible in the user space at all. [32-bit user space if req with command] ==> [IOCTL] ==> [64-bit KERNEL] ==> [reads register copies result into ifreq->ifr_data in kernel] ==> [The copied data is not visible in the user code]. Since the data i require is having a length of only 4 bytes, i used the ifr_data field itself as a buffer instead of using it as a pointer to a buffer because i see that the ifreq structure is of 32 bytes length and ifr_name is part of a union which has a size of 16 bytes. I tried to do some debugging on this issue and found these: the struct ifreq is 32 byte in 32-bit user space but is 40 bytes in kernel space, this is probably because of the size of sockaddr inside ifreq which is different for 64-bit, also copy_from/to_user is not required because do_ioctl is already working on a copy of the ifreq buffer. I did some googling and found suggestions to use compat_ioctl to do the porting, but that is pertaining to using the file_operations structure, netdevice does not have a compat_ioctl, does it? Any help is appreciated in this regard. kind regards, mz. -- To unsubscribe from this list: send the line "unsubscribe linux-embedded" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
