Technicalities » build

Updating the kernel on the Nexus S

Mark Brown — Mon, 14 Feb 2011 13:12:15 +0000

Building the kernel for the Nexus S is straightforward – the kernel is public as one would expect so it’s simply a matter of building it using the standard Linux build system (the machine is called herring in the code). There is one gotcha, though – the driver for the BCM4329 WiFi controller is a loadable kernel module rather than being built into the image. This means you need to copy it onto the device filesystem separately to flashing the kernel itself if you’re only updating the kernel. The procedure I use for this is below – it’s straightforward but I’m posting it here to make it a bit more discoverable.

First we make the system partition writable:

adb root
adb remount

Then copy the BCM4329 driver over (the path to the driver here is running from the root of the kernel tree:

adb push drivers/net/wireless/bcm4329/bcm4329.ko /system/modules

Finally, reboot into the bootloader and flash the actual kernel:

adb reboot bootloader
fastboot flash zimage arch/arm/boot/zImage
fastboot reboot

Note that some of these commands may return before the operation they’ve started has completed so you may need to wait for the phone at various points.

As with updating the main system firmware the above requires an unlocked device which voids your warranty.

Building firmware images for Nexus S

Mark Brown — Tue, 04 Jan 2011 16:03:54 +0000

Since I couldn’t seem to readily find any useful instructions for building firmware images for the Nexus S I thought I’d publish some. In a clean directory this sequence of commands should result in a working set of application layer images. They assume you’ve already got all the Android build dependencies installed:

repo init -u git://android.git.kernel.org/platform/manifest.git -b gingerbread
repo sync
MYDROID=$(pwd)
export MYDROID
. ./build/envsetup.sh
make PRODUCT-full_crespo-user

The resulting images will be in the directory out/target/product/crespo. You can get this running on your device by flashing the boot, recovery and system images:

out/host/linux-x86/bin/fastboot flash boot out/target/product/crespo/boot.img
out/host/linux-x86/bin/fastboot flash recovery out/target/product/crespo/recovery.img
out/host/linux-x86/bin/fastboot flash system out/target/product/crespo/system.img

Note that using these firmware images will void any warranty you have on the phone – you’ll need to unlock the phone using fastboot oem unlock, but note that this is irreversible.

Similar instructions should work for Nexus One too, using passion instead of crespo in the make command above.

SCons DESTDIR support

Mark Brown — Thu, 27 Sep 2007 10:40:23 +0000

Michael, it’s not make that supports for DESTDIR – it’s the Makefiles that do it, usually as one of the many features picked up from automake. Half the problem SCons has with this is that there’s no similarly pervasive tool set to at least set standards (even people who don’t use automake often emulate the features that people actually use) and the focus has mostly been on pure make functionality so there’s really nothing there for installation and packaging. This has resulted in projects using SCons each coming up with their own approach to these things – which can boil down to no approach at all.

The situation for SCons ought to be improved fairly soon thanks to a pair Summer of Code projects from this year and last year which will together give SCons automake-style functionality – hopefully once they’re merged people will start using them when they distribute their software. In the meantime you could always ask upstream to implement DESTDIR support.