USB/IP kernel modules build script for Sailfish OS

1. License
----------
Copyright (c) 2015 Lcferrum

This program comes with no warranty.
You must use this program at your own risk.
Licensed under BSD license - see LICENSE file for details.

2. About
--------
USB/IP kernel modules build script with accompanying .spec file. Builds kernel
module RPM package (aka KMP) compatible with Sailfish OS.

Resulting RPM supports relocation (default relocation prefix is 
/lib/modules/KERNEL_VERSION) and contains following modules:

	- usbip-core.ko
	- usbip-host.ko
	- vhci-hcd.ko
	
RPM will just install these modules on the system and update module
dependencies. It won't do modprobe, install services or anything similar.

3. Where to get
---------------
Main project homepage is at GitHub:

	https://github.com/lcferrum/usbip-kmp
	
Already built USB/IP kernel module RPMs can be downloaded from OpenRepos:

	https://openrepos.net/content/lcferrum/usbip-kernel-modules

4. Prerequisites
----------------
You should be familiar with Sailfish OS SDK and have it already installed.
If not, go to https://sailfishos.org/ to download latest SDK version and read
some FAQs and guides on using that SDK. At least you should know how to run Mer
build engine and connect to it over SSH.

Also you will need Sailfish OS kernel sources and (optional) Module.symvers
file. Both sources and Module.symvers file should match OS version
that will be used with USB/IP kernel modules. Write down Sailfish OS version
(Settings->System->About product) and it's kernel version ('uname -r' in
Terminal app) - build script will need this information.

You can download Sailfish OS kernel sources (.tar.gz archive) from KonstaT's
repo:

	https://github.com/KonstaT/sailfishos_kernel_jolla_msm8930
	
Or get official Jolla's DVD with open source packages. Kernel tarball is in
kernel-adaptation-sbj directory on this DVD. Contents of this DVD are also
available online:

	http://releases.sailfishos.org/sources
	
Module.symvers for particular OS version is available elsewhere. Google for it.
Without it build script will have to rebuild whole kernel. It's a long process
(up to several hours) and will require a lot of Mer VM's disc space. It will
actually require more disc space than VM curently provides (4 GB as for
SDK Beta 1502). So edit VM's HDD size (with VBoxManage) and expand main
partition (with something like gparted live CD). 8 GB should be enough.
	
5. Usage
--------      
Connect to Mer build engine and run the build script like this (.spec file
should be in the same directory as script):                        
	
	./build-usbip-kernel-modules.sh KERNEL_SOURCE SAILFISH_OS_VERSION ACTUAL_JOLLA_KERNEL_VERSION [MODULE_SYMVERS]
	
KERNEL_SOURCE and MODULE_SYMVERS are paths to kernel tarball and Module.symvers
files respectively. MODULE_SYMVERS parameter is optional, but without it RPM
build would take a lot of time (see 'Prerequisites' section).

SAILFISH_OS_VERSION is Sailfish OS version for which kernel modules are being
built. ACTUAL_JOLLA_KERNEL_VERSION - it's kernel version. Kernel sources
and Module.symvers file (if present) should match Sailfish OS version!
Sailfish OS version can be found in Settings->System->About product section of
Jolla phone. Type 'uname -r' in Jolla Terminal app to find out OS' kernel
version.

After the script finishes, there will be several new directories created by
rpmbuild process in the same directory as the script. RPM package with USB/IP
kernel modules will be in the RPMS/armv7hl directory:

	usbip-kernel-modules-X.X.X.X-1.jolla.armv7hl.rpm
	
Where X.X.X.X is Sailfish OS version for which it was built.

5. Sailfish OS kernel versions
------------------------------
In case when kernel sources for the target Sailfish OS version are not
available, USB/IP kernel modules can be built using latest available sources.
Though it's not guaranteed that resulting modules will work with target
Sailfish OS version. Use the following table to get full kernel version string
for the available Sailfish OS kernel sources (because it's actually not
mentioned anywhere in the source code):

    Sailfish OS version   kernel version
    -------------------   -------------------
    1.1.1.27              3.4.98.20141031.3
    1.1.2.16              3.4.98.20141219.1.1
    1.1.6.27              3.4.106.20150416.1

To install resulting RPM use relocation prefix:

	rpm -ivh --prefix=/lib/modules/$(uname -r) usbip-kernel-modules-X.X.X.X-1.jolla.armv7hl.rpm
	
You'll need to use --force option with modprobe to add modules to kernel when
modules' version doesn't match kernel version.