Greg KH wrote: > On Fri, May 29, 2009 at 04:21:20PM -0400, Daniel Drake wrote: > >> Joseph Jezak wrote: >> >>> Hi, >>> >>> Recently, I tested libusb on a PowerPC processor and found that devices >>> were not enumerating. This was due to the assumption that the length of >>> the configuration descriptor was swapped to big endian, as with other 16 >>> bit values in the descriptor. It appears (in core/config.c) that this >>> value is actually always left as a little endian value. >>> >>> A few questions: >>> 1. Is this a bug or expected behavior? >>> 2. Is it documented anywhere? >>> 3. Should user space applications that depend on /dev/bus/usb assume >>> that this value is always little endian? >>> >> To clarify, the surprise that we found is that the wTotalLength field >> from the device descriptor in (e.g.) /dev/bus/usb/001/001 is bus endian, >> not host endian, but the documentation in proc_usb_info.txt says: >> >> >>> These files can be read as binary data. The binary data consists >>> of first the device descriptor, then the descriptors for each >>> configuration of the device. Multi-byte fields in the device and >>> configuration descriptors, but not other descriptors, are converted >>> to host endianness by the kernel. >>> >> without mention of this exception. >> > > Hm, this happened years ago, are you sure this is a new thing? > > thanks, > > greg k-h > > As far as I can tell, it's at least a current thing. This machine is running a 2.6.30-rc4 kernel with a number of local patches unrelated to USB. If you'd like me to try other kernels to figure out when it changed, please let me know. -Joe -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
