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. Daniel -- 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
