Gerd Knorr wrote: > Johannes Stezenbach <js@xxxxxxxxxxx> writes: > > > I have no idea if we need to do something special to support this, > > although I've seen that there's this compat_ioctl in > > struct file_operations. Does someone have a clue? > > Yes, compat_ioctl is for 32bit apps. Had a quick look at the structs > and they seem to be identical in 32 and 64 bit. I think simply > hooking the ioctl callback into both ioctl and compat_ioctl could do > the trick for the frontend device. > > In case you'll have fields like "long" or "void*" in the ioctl structs > which have different sizes for 32/64 bit apps compat_ioctl would have > to take care to handle the 32-bit cases correctly. Browse through the > kernel source code, there should be quite a few examples ;) It seems none of the DVB API headers use long or void* fields, except osd.h, so conversion should be easy. BUT: http://lwn.net/Articles/119652/ If I understand that correctly, compat_ioctl does not acquire the BKL (big kernel lock), so if we want to add compat_ioctl we must either audit all code if it depends on the BLK (I guess not, but I'm not sure), or call lock/unlock_kernel() explicitely in our compat_ioctl handlers. Johannes
