Add libusb compile information to README

README

@@ -106,6 +106,51 @@ Dependencies:
 	(This is only required for ASIC+FPGA support)
 
 
+Before compiling cgminer, if you are using any USB devices you need to build libusb
+
+	Some versions of libsub have a timeout bug.
+	This shows up mostly with the ICA and AMU USB1.1 devices.
+
+	To compile cgminer with a known working version of libusb
+	First install udev-dev via one of:
+		Ubuntu derivatives: apt-get install libudev-dev
+		Arch: it should be installed by default as part of systemd
+		Fedora: yum install libgudev1
+		Mingw: not required
+
+	In the cgminer folder create a subfolder called libusb
+		mkdir libusb
+		cd libusb
+	Now, in that folder get and extract the known working libusb
+	 libusb-1.0.16-rc10.tar.bz2
+
+	It is available here:
+	 http://sourceforge.net/projects/libusb/files/libusb-1.0/libusb-1.0.16-rc10/
+
+	In linux and mingw you extract with:
+		tar -xvf libusb-1.0.16-rc10.tar.bz2
+
+	Then to build it:
+		cd libusb-1.0.16-rc10
+		./configure
+		make
+		cd ../..
+
+	Now when you configure cgminer as listed further below in the build
+	instructions, for all the USB devices you must add libusb as follows:
+		LIBUSB_CFLAGS="-I./libusb/libusb-1.0.16-rc10/libusb" LIBUSB_LIBS="./libusb/libusb-1.0.16-rc10/libusb/.libs/libusb-1.0.a -ludev" ./configure --enable-bflsc --enable-icarus --enable-bitforce --enable-modminer --enable-ztex --enable-avalon
+
+	On Fedora18 you need -lrt also:
+		LIBUSB_CFLAGS="-I./libusb/libusb-1.0.16-rc10/libusb" LIBUSB_LIBS="./libusb/libusb-1.0.16-rc10/libusb/.libs/libusb-1.0.a -ludev -lrt" ./configure --enable-bflsc --enable-icarus --enable-bitforce --enable-modminer --enable-ztex --enable-avalon
+
+	On Windows mingw:
+		LIBUSB_CFLAGS="-I./libusb/libusb-1.0.16-rc10/libusb" LIBUSB_LIBS="./libusb/libusb-1.0.16-rc10/libusb/.libs/libusb-1.0.dll.a" ./configure --enable-bflsc --enable-icarus --enable-bitforce --enable-modminer --enable-ztex --enable-avalon
+
+	After compiling on windows you need to copy
+		./libusb/libusb-1.0.16-rc10/libusb/.libs/libusb-1.0.dll
+	into the current cgminer folder before running cgminer
+
+
 CGMiner specific configuration options:
 	--disable-opencl        Override detection and disable building with opencl
 	--disable-adl           Override detection and disable building with adl