I am trying to build an AOSP kernel, but I can't make the resulting boot.img small enough to flash and boot it. It contains the compressed kernel with appended dtbs and the initramfs. My intention is to fuzz-test drivers using Syzkaller. I'm currently using a Pixel XL (marlin). I use kernel branch android-msm-marlin-3.18-pie-qpr3 (tried related ones as well) and I'm trying various gcc-based toolchains. For AOSP I picked Pie (tag android-9.0.0_r46, build PQ3A.190801.002). However, please note that this is a general question, it's not fuzzing-, kernel- or device-specific.
My requirements are:
Keep vendor-introduced drivers (because they are what I want to fuzz)
Enable KASAN and KCOV (and their dependencies)
Enable CONFIG_DEBUG_INFO
Keep printk and the like
Things I tried and ideas I have:
Tuning kernel config - This helps to some extend, but it's just not enough. I'm already using for example CONFIG_CC_OPTIMIZE_FOR_SIZE=y, CONFIG_CORE_SMALL=y, CONFIG_NET_SMALL=y, CONFIG_KASAN_OUTLINE=y, CONFIG_TRIM_UNUSED_KSYMS=y, CONFIG_SLOB=y, ...
Compress kernel (and/or initramfs) with xz or lzma - The idea seems promising. I noticed the kernel build system for arm64 neither supports xz nor lzma out of the box (not sure why?), so I patched it myself to get it building. The build succeeds and the resulting Image.xzkern-dtb or Image.lzma-dtb seems okay, however when attempting to boot it (serial debugging logs):
[5710] partition_enable_wp: group 0 not defined
[5720] DTB offset is incorrect, kernel image does not have appended DTB
[5720] Device info 0x00000131/00010001/0x00010001/0, pmic 0x20009/0x455013/0x0/0x0
[5740] ERROR: Appended Device Tree Blob not found
[5740] panic (frame 0x83a86848):
...
I verified that the DTBs are present and the kernel is compressed as intended. My question here: Is it possible at all? Does the Android bootloader even support xz/lzma? I hardly found any info about that online. Is there any way to use xz or lzma compressed kernels to boot Android?
Resize the boot partition - It seems difficult but possible, not sure if worth attempting. Can you recommend any resources or tools for that?
Removing unnecessary features from initramfs
Link-Time Optimization - I could not get it to work with the AOSP kernel, no matter what gcc version I use. Any tips?
Building features as modules instead of built-in - The build won't succeed with any config I try, even when building only single features as module (with different compiler or linker errors depending on the config). Do you have any guides or tips?
I also followed the tutorial on building a Pixel kernel with KASAN and KCOV on the AOSP homepage (link). I had some problems with it, but eventually (using Linaro GCC 5.5.0, with some config changes and without CONFIG_DEBUG_INFO) I could get it building and booting. Nice as a proof-of-concept but not what I need, since I had to skip some required features.
I'm pretty much stuck and already spent some weeks on that problem. Are there any other options? I'd be happy to get it booting in any way. I'll happily provide any details and logs, but felt like it's already a very long post. Thank you a lot in advance!
I found a solution working for me. It's a close call though, probably not enough size reduction for different situations. Anyways, it might help others.
I'm using pigz instead of the default gzip tool, which offers an even higher compression level with the -11 switch. Increasing the number of optimization iterations with -I 45 further improved it (default is 15). This squeezes out the last bit that I need: The resulting Image.gz-dtb is about 2.5% smaller than before.
These are the changes I made to the kernel build system (assuming pigz will be in your PATH at build time):
diff --git a/arch/arm64/boot/Makefile b/arch/arm64/boot/Makefile
index b7cf2a498c19..7dfd438e997b 100644
--- a/arch/arm64/boot/Makefile
+++ b/arch/arm64/boot/Makefile
## -30,7 +30,8 ## $(obj)/Image: vmlinux FORCE
$(call if_changed,objcopy)
$(obj)/Image.gz: $(obj)/Image FORCE
- $(call if_changed,gzip)
+# $(call if_changed,gzip)
+ $(call if_changed,pigz)
$(obj)/Image.lz4: $(obj)/Image FORCE
$(call if_changed,lz4)
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index c2b437eb23d5..73d4581f7531 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
## -272,6 +272,11 ## quiet_cmd_gzip = GZIP $#
cmd_gzip = (cat $(filter-out FORCE,$^) | gzip -n -f -9 > $#) || \
(rm -f $# ; false)
+
+quiet_cmd_pigz = PIGZ $#
+cmd_pigz = (cat $(filter-out FORCE,$^) | pigz -n -f -11 -I 45 > $#) || \
+ (rm -f $# ; false)
+
# DTC
# ---------------------------------------------------------------------------
It flashes and boots fine, even boots in a reasonable time, as opposed to what I had before.
Related
I'm porting android to a display device, and have nearly completed this. The device use the Freescale/NXP i.MX6 Dual Lite Soc. The Android version used is Android 8.0.0, and the build is based on the Board Support Packages from NXP/Freescale (link below).
https://www.nxp.com/support/developer-resources/software-development-tools/i.mx-developer-resources/android-os-for-i.mx-applications-processors:IMXANDROID?tab=Design_Tools_Tab
The OS builds fine, and the images (u-boot, boot.img, system.img, vendor.img) resuling from the "make" process works perfercly fine on the device. So my last step is basically to sign the images, and this is where I struggle to get stuff working.
I am following the the guide found here:
https://source.android.com/devices/tech/ota/sign_builds
After completing the steps, I use the now signed images found in the "signed-img.zip" file to flash the device (using the NXP Manufacturing Tool, and not Fast Boot). However, the device now fails to boot the Kernel, giving me an error that the DTB is missing.
Hit any key to stop autoboot: 0
boota mmc0
kernel # 14008000 (8183104)
ramdisk # 15000000 (2036048)
## Booting Android Image at 0x12000000 ...
Kernel load addr 0x14008000 size 7992 KiB
Kernel command line: console=ttymxc0,115200 init=/init video=mxcfb0:dev=ldb video=mxcfb1:off video=mxcfb2:off video=mxcfb3:off vmalloc=128M androidboot.console=ttymxc0 consoleblank=0 ldo_active=on androidboot.hardware=sedevices cma=448M android.selinux=permissive android.dm_verify=disable androidboot.selinux=enforce androidboot.dm_verity=disable androidboot.storage_type=emmc loglevel=8 vt.global_cursor_default=0 buildvariant=userdebug androidboot.serialno=0b2861d4df668b47 androidboot.soc_type=imx6dl androidboot.storage_type=emmc
ERROR: Did not find a cmdline Flattened Device Tree
Could not find a valid device tree
resetting ...
I've narrowed the problem down to the very first step in the guide, where "make dist" is executed in the build directory. This produces a number of ZIP files in the "out/dist" folder, which is processed further in the following steps in the guide. I've tried flashing the device with the images produced in this step (found in the resulting "out/dist/*-img-*.zip" file), and this produces the exact same issue.
So my question is, what does really "make dist" do which cause the DTB to be missing in the "boot.img"? I would've expected it to use the already working "boot.img" found in "out/target/product//". But it instead seems to re-build this image, and in this case not include the DTB. As with so many other aspects of building Android from Source, the workings of "make dist" does not seem to be explained anywhere in the documentation.
I hope anyone with some experience in building Android from source knows something about this, because I seem to be royally stuck.
Just FYI; when I flash the "boot.img" produced after a normal "make", the output after U-boot is as follows:
Hit any key to stop autoboot: 0
boota mmc0
Error: blob decap job completed with errors 0x2000081A
In boota get fastboot lock status error. Set lock status
kernel # 14008000 (8183104)
ramdisk # 15000000 (2036754)
fdt # 14f00000 (40998)
## Booting Android Image at 0x12000000 ...
Kernel load addr 0x14008000 size 7992 KiB
Kernel command line: console=ttymxc0,115200 init=/init video=mxcfb0:dev=ldb video=mxcfb1:off video=mxcfb2:off video=mxcfb3:off vmalloc=128M androidboot.console=ttymxc0 consoleblank=0 ldo_active=on androidboot.hardware=sedevices cma=448M android.selinux=permissive android.dm_verify=disable androidboot.selinux=enforce androidboot.dm_verity=disable androidboot.storage_type=emmc loglevel=8 vt.global_cursor_default=0 buildvariant=userdebug androidboot.serialno=0b2861d4df668b47 androidboot.soc_type=imx6dl androidboot.storage_type=emmc
## Flattened Device Tree blob at 14f00000
Booting using the fdt blob at 0x14f00000
Loading Kernel Image ... OK
Using Device Tree in place at 14f00000, end 14f0d025
switch to ldo_bypass mode!
Starting kernel ...
It seem NXP/Freescale have modified the Build Scripts in their AOSP Board Support Package, and broken the DTB inclusion in the process. It may seem like they where happy when the output from the standard "make" process worked on their Dev Board, and never bothered checking if it was possible to create working signed Release images with it.
The mechanism to include a DTB in the dist package was in place (specifying the location of the DTB in BOARD_KERNEL_DTS), and was also used for their "make otapackage" target. However, that target only generates an unsigned (or signed with dev keys) OTA package, which can not be used with the signing scripts.
In order to make it work as it should, I had to make a small change in the main Makefile which specifies the location of the DTB defined in the BoardConfig.mk. The change was simple enough to make, but the hard part was figuring out where the problem was and how it was intended to work in the first place.
The following patch in "build/make/" fixes the issue, as long as a BoardConfig.mk ONLY specifies one DTB (which at least suits my needs):
diff --git a/core/Makefile b/core/Makefile
index a650565a1..92f3025a9 100644
--- a/core/Makefile
+++ b/core/Makefile
## -621,6 +621,19 ## ifdef INTERNAL_KERNEL_CMDLINE
INTERNAL_BOOTIMAGE_ARGS += --cmdline "$(INTERNAL_KERNEL_CMDLINE)"
endif
+# NOTE! This script has a defect which cause the kernel DTB to be left out when ever 'make dist'
+# is executed. The following addition "fixes" this by adding the first dtb specified in the
+# BoardConfig.mk file. (I would guess in most cases there is never more than one!)
+ifdef dist_goal
+ifndef BOARD_KERNEL_DTS
+ifdef TARGET_BOARD_DTS_CONFIG
+DTS_BOARD=$(word 2, $(subst :, ,$(word 1, $(TARGET_BOARD_DTS_CONFIG))))
+BOARD_KERNEL_DTS="$(KERNEL_OUT)/$(DTS_BOARD)"
+$(info FIXUP: Defining BOARD_KERNEL_DTS:=[$(BOARD_KERNEL_DTS)] for BOOT packaging)
+endif
+endif
+endif
+
INTERNAL_MKBOOTIMG_VERSION_ARGS := \
--os_version $(PLATFORM_VERSION) \
--os_patch_level $(PLATFORM_SECURITY_PATCH)
I like to crosscompile Perl for the Android x86 emulator. But I got a PIE (position independent executables) error on running Configure... Based on this and this tutorial.
Specs:
NDK version 14
Perl 5.22.1.
x86 Android emulator built with AOSP - Android 7.1.1
I set following variables:
export ANDROID_NDK=/home/fabian/Android/Sdk/ndk-bundle
export TARGET_ARCH=x86
export ANDROID_TOOLCHAIN=/tmp/toolchain-x86
export SYSROOT=$ANDROID_TOOLCHAIN/sysroot
export TARGETDIR=/data/local/perl
export GCC=i686-linux-android-gcc
export PATH=$PATH:$ANDROID_NDK/toolchains/x86-4.9/prebuilt/linux-x86_64/bin
Then I build the toolchain with following command:
$ANDROID_NDK/build/tools/make-standalone-toolchain.sh --platform=android-23 --install-dir=$ANDROID_TOOLCHAIN --toolchain=x86-4.9
and get this (correct?) output:
HOST_OS=linux
HOST_EXE=
HOST_ARCH=x86_64
HOST_TAG=linux-x86_64
HOST_NUM_CPUS=4
BUILD_NUM_CPUS=8
Auto-config: --arch=x86
Toolchain installed to /tmp/toolchain-x86.
Then I start the ./Configure command:
./Configure -des -Dusedevel -Dusecrosscompile -Dtargetrun=adb -Dcc=i686-linux-android-gcc -Dsysroot=$SYSROOT -Dtargetdir=$TARGETDIR -Dtargethost=emulator-5554
and got this output:
First let's make sure your kit is complete. Checking...
Would you like to see the instructions? [n]
Locating common programs...
Checking compatibility between /bin/echo and builtin echo (if any)...
Symbolic links are supported.
Checking how to test for symbolic links...
You can test for symbolic links with 'test -h'.
Using targetarch i686-linux-android.
Using targethost emulator-5554.
Building host miniperl and generate_uudmap binaries
Using targethost emulator-5554.
Guessing targetuser root.
Guessing targetport 22.
Using '/home/fabian/Desktop/Testimages/perl-5.22.1/Cross/run-adb' for remote execution,
and '/home/fabian/Desktop/Testimages/perl-5.22.1/Cross/from-scp' and '/home/fabian/Desktop/Testimages/perl-5.22.1/Cross/to-scp'
for remote file transfer.
Good, your tr supports [:lower:] and [:upper:] to convert case.
Using [:upper:] and [:lower:] to convert case.
aix_3 dragonfly irix_4 nonstopux stellar
aix_4 dynixptx irix_5 openbsd sunos_4_0
aix dynix irix_6_0 opus sunos_4_1
altos486 epix irix_6_1 os2 super-ux
amigaos esix4 irix_6 os390 svr4
atheos fps isc_2 os400 svr5
aux_3 freebsd isc posix-bc ti1500
bitrig freemint linux-android powerux ultrix_4
bsdos genix linux qnx umips
catamount gnukfreebsd lynxos riscos unicosmk
convexos gnuknetbsd midnightbsd sco_2_3_0 unicos
cxux gnu mips sco_2_3_1 unisysdynix
cygwin greenhills mirbsd sco_2_3_2 utekv
darwin haiku mpc sco_2_3_3 uwin
dcosx hpux ncr_tower sco_2_3_4 vos
dec_osf i386 netbsd sco
dos_djgpp interix newsos4 solaris_2
Which of these apply, if any? [linux-android]
"./a.out": error: only position independent executables (PIE) are supported.
Aborted
You don't have an ELF gcc. I will use dld if possible. If you are
using a version of DLD earlier than 3.2.6, or don't have it at all, you
should probably upgrade. If you are forced to use 3.2.4, you should
uncomment a couple of lines in hints/linux.sh and restart Configure so
that shared libraries will be disallowed.
Disabling ndbm. This will generate a Whoa There message in Configure.
Read hints/linux.sh for further information.
Operating system name? [linux-android]
Operating system version? [7.1.1]
Installation prefix to use? (~name ok) [/usr/local]
AFS does not seem to be running...
What installation prefix should I use for installing files? (~name ok)
[/usr/local]
Getting the current patchlevel...
Build a threading Perl? [n]
Build Perl for multiplicity? [n]
Use which C compiler? [i686-linux-android-gcc]
Checking for GNU cc in disguise and/or its version number...
"./try": error: only position independent executables (PIE) are supported.
Aborted
Now, how can we feed standard input to your C preprocessor...
Directories to use for library searches?
[/tmp/toolchain-x86/sysroot/usr/lib/../lib /tmp/toolchain-x86/sysroot/usr/lib]
What is the file extension used for shared libraries? [sa]
Make shared library basenames unique? [n]
Hmm. Based on the hints in hints/linux-android.sh,
the recommended value for $d_libname_unique on this machine was "define"!
Keep the recommended value? [y]
Build Perl for SOCKS? [n]
Try to use long doubles if available? [n]
Checking for optional libraries...
What libraries to use? [-lm -lc]
What optimizer/debugger flag should be used? [-O2]
Any additional cc flags?
[-DOVR_DBL_DIG=14 --sysroot=/tmp/toolchain-x86/sysroot]
Let me guess what the preprocessor flags are...
Any additional ld flags (NOT including libraries)?
[ --sysroot=/tmp/toolchain-x86/sysroot]
Checking your choice of C compiler and flags for coherency...
I've tried to compile and run the following simple program:
#include
int main() { printf("Ok\n"); return(0); }
I used the command:
i686-linux-android-gcc -o try -O2 -DOVR_DBL_DIG=14 --sysroot=/tmp/toolchain-x86/sysroot --sysroot=/tmp/toolchain-x86/sysroot try.c -lm -lc
/home/fabian/Desktop/Testimages/perl-5.22.1/Cross/run-adb-shell ./try
and I got the following output:
The program compiled OK, but exited with status 134.
You have a problem. Shall I abort Configure [y]
Ok. Stopping Configure.
OK I have to set the flags
Modify config.sh to enable PIE support. Append “-fPIE” to ccflags and
“-fPIE -pie” to ldflags. Then rerun configure to ensure this is
applied.
But there is no config.sh in the perl folder, so I tried this ./Configure command:
`./Configure -des -Dusedevel -Dusecrosscompile -Dtargetrun=adb -Dcc=i686-linux-android-gcc -Dsysroot=$SYSROOT -Dtargetdir=$TARGETDIR -Dtargethost=emulator-5554 -Dccflags='-fPIE' Dldflags='-fPIE -pie'`
but same problem again...
First let's make sure your kit is complete. Checking...
Would you like to see the instructions? [n]
Locating common programs...
Checking compatibility between /bin/echo and builtin echo (if any)...
Symbolic links are supported.
Checking how to test for symbolic links...
You can test for symbolic links with 'test -h'.
Using targetarch i686-linux-android.
Using targethost emulator-5554.
Building host miniperl and generate_uudmap binaries
Using targethost emulator-5554.
Guessing targetuser root.
Guessing targetport 22.
Using '/home/fabian/Desktop/Testimages/perl-5.22.1/Cross/run-adb' for remote execution,
and '/home/fabian/Desktop/Testimages/perl-5.22.1/Cross/from-scp' and '/home/fabian/Desktop/Testimages/perl-5.22.1/Cross/to-scp'
for remote file transfer.
Good, your tr supports [:lower:] and [:upper:] to convert case.
Using [:upper:] and [:lower:] to convert case.
aix_3 dragonfly irix_4 nonstopux stellar
aix_4 dynixptx irix_5 openbsd sunos_4_0
aix dynix irix_6_0 opus sunos_4_1
altos486 epix irix_6_1 os2 super-ux
amigaos esix4 irix_6 os390 svr4
atheos fps isc_2 os400 svr5
aux_3 freebsd isc posix-bc ti1500
bitrig freemint linux-android powerux ultrix_4
bsdos genix linux qnx umips
catamount gnukfreebsd lynxos riscos unicosmk
convexos gnuknetbsd midnightbsd sco_2_3_0 unicos
cxux gnu mips sco_2_3_1 unisysdynix
cygwin greenhills mirbsd sco_2_3_2 utekv
darwin haiku mpc sco_2_3_3 uwin
dcosx hpux ncr_tower sco_2_3_4 vos
dec_osf i386 netbsd sco
dos_djgpp interix newsos4 solaris_2
Which of these apply, if any? [linux-android]
"./a.out": error: only position independent executables (PIE) are supported.
Aborted
You don't have an ELF gcc. I will use dld if possible. If you are
using a version of DLD earlier than 3.2.6, or don't have it at all, you
should probably upgrade. If you are forced to use 3.2.4, you should
uncomment a couple of lines in hints/linux.sh and restart Configure so
that shared libraries will be disallowed.
Disabling ndbm. This will generate a Whoa There message in Configure.
Read hints/linux.sh for further information.
Operating system name? [linux-android]
Operating system version? [7.1.1]
Installation prefix to use? (~name ok) [/usr/local]
AFS does not seem to be running...
What installation prefix should I use for installing files? (~name ok)
[/usr/local]
Getting the current patchlevel...
Build a threading Perl? [n]
Build Perl for multiplicity? [n]
Use which C compiler? [i686-linux-android-gcc]
Checking for GNU cc in disguise and/or its version number...
"./try": error: only position independent executables (PIE) are supported.
Aborted
Now, how can we feed standard input to your C preprocessor...
Directories to use for library searches?
[/tmp/toolchain-x86/sysroot/usr/lib/../lib /tmp/toolchain-x86/sysroot/usr/lib]
What is the file extension used for shared libraries? [sa]
Make shared library basenames unique? [n]
Hmm. Based on the hints in hints/linux-android.sh,
the recommended value for $d_libname_unique on this machine was "define"!
Keep the recommended value? [y]
Build Perl for SOCKS? [n]
Try to use long doubles if available? [n]
Checking for optional libraries...
What libraries to use? [-lm -lc]
What optimizer/debugger flag should be used? [-O2]
Any additional cc flags?
[-DOVR_DBL_DIG=14 -fPIE --sysroot=/tmp/toolchain-x86/sysroot]
Let me guess what the preprocessor flags are...
Any additional ld flags (NOT including libraries)?
[ --sysroot=/tmp/toolchain-x86/sysroot]
Checking your choice of C compiler and flags for coherency...
I've tried to compile and run the following simple program:
#include
int main() { printf("Ok\n"); return(0); }
I used the command:
i686-linux-android-gcc -o try -O2 -DOVR_DBL_DIG=14 -fPIE --sysroot=/tmp/toolchain-x86/sysroot --sysroot=/tmp/toolchain-x86/sysroot try.c -lm -lc
/home/fabian/Desktop/Testimages/perl-5.22.1/Cross/run-adb-shell ./try
and I got the following output:
"./try": error: only position independent executables (PIE) are supported.
Aborted
The program compiled OK, but exited with status 134.
You have a problem. Shall I abort Configure [y]
Ok. Stopping Configure.
But now the ccflag is set how you can see in the last lines...
Did I miss something?
(The i9100 and i9100p phones have Exynos 4210 SoC which includes Cortex A9 dual core 1.2Ghz processor which supports NEON.)
I will compile the latest busybox source snapshot available and upload it for everyone for free on internet and maybe even make my own free BusyboxInstaller.apk (I already downloaded today's 14th March snapshot from the official website) because so many busybox installers have very outdated versions and I want to take advantage of possible optimizations for the Cortex A9 cpu.
(NEON technology is a 128-bit SIMD (Single Instruction, Multiple Data) architecture extension.
It can can accelerate multimedia and signal processing algorithms such as video encode/decode, 2D/3D graphics, gaming, audio and speech processing, image processing, telephony, and sound synthesis.)
1 does such as mean it will also benefit my busybox?
2 What other instructions/anythingelse I can use to optimize for i9100 devices?
3 Can I compile on my phone instead of PC with only 1x2Ghz and 2GB RAM? I think it should be much quicker because it has 2x1.5GHz and 1GB RAM (I overclock only a bit) versus 1x2GHz, am I right?
4 How to compile busybox?
What are these options for?
Force NOMMU build
Additional CFLAGS
Additional LDFLAGS
Additional LDLIBS
all in general configuration and Busybox Library Tuning and debug (I googled for each for a few hours but nothing satisfactory)
What kind of applet links to install?
(./_install) BusyBox installation prefix
**I have eeror when following vinayhunachyai instructions.
make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- install
/home/euphoria/Sourcery/busybox/scripts/gcc-version.sh: line 11: arm-none-linux-gnueabi-gcc: command not found
CC applets/applets.o
/bin/sh: 1: arm-none-linux-gnueabi-gcc: not found
scripts/Makefile.build:197: recipe for target 'applets/applets.o' failed
make[1]: *** [applets/applets.o] Error 127
Makefile:372: recipe for target 'applets_dir' failed
make: *** [applets_dir] Error 2
How to compile busybox?
1st download toolchain. You can refer to this: Advice regarding installing ARM toolchain on Ubuntu VM (64bit)
untar new source-code
create default config
make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- defconfig
A default configuration file is created.
update config to change it to our needs:
make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- menuconfig
The option to compile Busybox as a static executable, so that we don’t have to copy the dynamic libraries inside the root filesystem. The setting can be found in “Busybox Settings --> Build Options“.
Also, select what utilities you want embedded in Busybox.
Then, the following command builds Busybox and creates a directory called _install containing the root filesystem tree:
make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- install.
Compile statically. If you compile dynamically then you need to copy libraries to target.
For more details see this link: http://balau82.wordpress.com/2010/03/27/busybox-for-arm-on-qemu/
For Android you can use config android_defconfig and build with examples/android-build.
I successfully used busybox patched by sherpya: his config sherpya_android_defconfig and slightly modified build script examples/android-build.
I've downloaded Android source code. Now I want to make it for my own device (LG GT540). I heard that you need to create some 'Device configuration' for that. Although several developers have already created device configurations for my device, but I want to create my own, just for learning.I saw a lot of files like BoardConfig.mk, AndroidProducts.mk, etc. But don't know what they do. Besides they contain a lot of configurations. Over that, there's not a good documentation for that.Can anyone experienced with Android porting and device configurations help me?
Right... So you want to build your own device tree, read on.
Disclaimer: this is by no means complete, and there will be omissions as have explained all this top of my head and copied pasted certain bits that I have here on my own device tree.
The device tree, for example, /device/lg/gt540would consist of the following make files:
Android.mk - this will tell the build system to include and to build sources specifically for your device. See below, for an example. This is dependant on the device and hardware, you could have libsensors, liblights, libcamera subdirectories under the example device tree, i.e. /device/lg/gt540/libsensors, /device/lg/gt540/liblights, /device/lg/gt540/libcamera etc.
AndroidBoard.mk - this is for the kernel, the build system uses that to drop the kernel image in place (more about this in a few minutes)
AndroidProducts.mk - specifies the appropriate device's make file, to use for building. i.e. /device/lg/gt540/device_gt540.mk, this is specific also.
device_xxxxx.mk - specifies the properties and extras to copy over into the final output, in this case, it could be for example, device_gt540.mk
BoardConfig.mk - This is the meat of it all, this is where compiler conditional flags are set, partition layouts, boot addresses, ramdisk size, and so on.
Lets peek into each of those to give a glance as to where it all fits in.
Android.mk:
ifeq ($(TARGET_BOOTLOADER_BOARD_NAME),xxxxx)
include $(call all-named-subdir-makefiles, recovery libsensors liblights libcamera ....)
endif
This is how the build will use that to build recovery, sensors, lights and camera (of course there will be more), its saying 'Yo Builder, go into each of the directories specified, and build the respective sources plskthxbai'
AndroidBoard.mk:
LOCAL_PATH := device/lg/gt540/
#
# Boot files
#
TARGET_PREBUILT_KERNEL := $(LOCAL_PATH)/kernel
file := $(INSTALLED_KERNEL_TARGET)
ALL_PREBUILT += $(file)
$(file): $(TARGET_PREBUILT_KERNEL) | $(ACP)
$(transform-prebuilt-to-target)
Now this, is telling the build system, to be able to drop this kernel into the out/target/product/lg/gt540 (notice the correlation with the device tree directory?)
AndroidProducts.mk:
PRODUCT_MAKEFILES := \
$(LOCAL_DIR)/device_gt540.mk
Its telling the build as in 'Yo Builder, read that device make file please and process it upon completion of build.'
*device_xxxxx.mk: (for this example, device_gt540.mk) *
PRODUCT_NAME := lg_gt540
PRODUCT_DEVICE := gt540
PRODUCT_MODEL := LG GT 540
PRODUCT_COPY_FILES += \
... specific ...
PRODUCT_PROPERTY_OVERRIDES := \
ro.com.android.dateformat=dd-MM-yyyy \
... more stuff ...
This is where all the specifics for the device such as drivers, proprietary libraries, supporting scripts specifically for the device, gets copied over to out/target/product/lg/gt540/system/ in this case. Notice how the overrides for the properties, these end up in the build.prop found in the root of the /system of the Android ROM.
BoardConfig.mk:
LOCAL_PATH:= $(call my-dir)
TARGET_NO_BOOTLOADER := true
TARGET_PREBUILT_KERNEL := device/lg/gt540/kernel
TARGET_PREBUILT_RECOVERY_KERNEL := device/lg/gt540/recovery_kernel
# This will vary from device!
TARGET_BOARD_PLATFORM := msm7k
TARGET_ARCH_VARIANT := armv6-vfp
TARGET_CPU_ABI := armeabi
TARGET_CPU_ABI := armeabi-v6l
TARGET_CPU_ABI2 := armeabi
# OpenGL drivers config file path
BOARD_EGL_CFG := device/lg/gt540/egl.cfg
# Dependant, not to be taken literally!
BOARD_GLOBAL_CFLAGS += -DHAVE_FM_RADIO
# Dependant, not to be taken literally!
BOARD_KERNEL_BASE := 0x02600000
# this will be device specific, and by doing cat /proc/mtd will give you the correct sizes
BOARD_BOOTIMAGE_PARTITION_SIZE := 0x00480000
BOARD_RECOVERYIMAGE_PARTITION_SIZE := 0x00480000
BOARD_SYSTEMIMAGE_PARTITION_SIZE := 0x0cf80000
BOARD_USERDATAIMAGE_PARTITION_SIZE := 0x0d020000
BOARD_FLASH_BLOCK_SIZE := 131072
That is an excerpt, notice how we specify kernel's base address, this is how the boot.img gets generated after compilation is done and yet again, gets dropped into out/target/product/lg/gt540/boot.img. Also, more importantly, we're telling the build system to use the target platform for cross-compiling the sources (*TARGET_BOARD_PLATFORM*/*TARGET_CPU_ABI*) There will be more information in there such as conditional flags to pass to the compiler, for an example. we specified the directive HAVE_FM_RADIO to tell it, when it comes to handling the source for the FM radio system, to conditionally compile parts of the source. Again, this is hardware specific and mileage will vary, also this applies to the address for boot. In a nutshell, this is saying 'Yo Builder, read the damn variables and remember them and apply them when cross-compiling those source files!'
Now that the internals of each of those Android build make-files are shown.
Now, onto the vendor/ part of it, in AOSP, simply, once again, correlation and corresponds with the device/ tree, as in continuing with this example, vendor/lg/gt540/ which gets picked up by the lunch. There's more make files in there but the general consensus is there's a directory called proprietary which contains the proprietary libs (due to close-source etc) that gets copied over. The copying over of the libraries gets specified in the file device-vendor-blobs.mk, in this case, gt540-vendor-blobs.mk.
When the magic happens by doing the following:
. build/envsetup.sh
This is reading in the entire entries found in each of the device/ subdirectories and "remembers them", so the build system knows what type of target is used etc.
When the . lunch gets invoked, a menu appears prompting to pick the device that is required to build. Now the last and final step to do the build...
make -j5 > buildlog.log 2>&1
I run multitail on another terminal and monitor the buildlog.log file to check and make sure its building.
This last step will depend on how many cores you have (n cores + 1 as a rule) and it takes a while to build, GB build takes 40mins on my laptop running Arch Linux 64bit, ICS build takes about 2hrs 30 mins. So mileage will vary on what type of horsepower your machine has.
When the build is done, a little bell goes off and at the bottom of the said log file, I see this:
Combining NOTICE files: out/target/product/xxxxx/obj/NOTICE.html
Target system fs image: out/target/product/xxxxx/obj/PACKAGING/systemimage_intermediates/system.img
Install system fs image: out/target/product/xxxxx/system.img
out/target/product/xxxx/system.img+ total size is 108776448
As matter of interest JBQ (Jean Baptiste Queru - the 'boss' for managing/distributing the source from Google), his build step is this...
make -j32
Yup! 32 cores! That..... is pretty powerful.
There is some information here: http://elinux.org/Android_Device
An excellent resource for anyone building Android for a device is here:
http://com.odroid.com/sigong/nf_file_board/nfile_board_view.php?bid=98
(A Practical Real-World Approach To Android Platform Development In ODROID)
Though some of the stuff in there is particular to the ODROID board, it still offers great insight into the inner workings of Android and the necessary customization for a new board.
If you're looking to get into the hardware side of things probably the single most informative resource I've found has been:
http://source.android.com/compatibility/overview.html
Read through the documentation they wrote for manufacturers looking to build android devices, it's the most thorough/complete reference you will find.
I'm facing a bug in a makefile build system (Android built under Linux) - some files are removed by an 'rm' command, and I can see that command in the build log.
How can I find the exact line in the makefiles which calls the 'rm' ? Is there any automated method?
For GNU Make you can do the following trick:
__shell := $(SHELL)
SHELL = \
$(warning making '$#'$(if $^, from '$^')$(if $?, because of '$?'))$(__shell)
SHELL variable is expanded each time when Make invokes a sub-shell to execute a recipe. In these lines it is replaced so that on each expansion it will print a target, its prerequisites and prerequisites that are newer than the target. Also each debug message is prepended with the file and line number of the rule being executed.
The same technique is used in GMD to set breakpoints to certain targets.
Assuming your make is a Gnu make, you can also pass some debugging options, like --debug=b (basic debugging messages, very often enough) or --debug=all which is the same as -d
Some files may be removed because they are intermediate. Read also about secondary files and precious files in make
You may try make -d -w and then grep your file from huge amount of output lines.