This is a brain dump. None of these instructions produces working images. It's just for reproducing an issue.
Currently the samsung kernel only needs one patch to build. It used to need two but it was fixed up stream. Now the only patch it needs is the common Ubuntu config. First I build vanilla CyanogenMod, but with the Ubuntu kernel config. This means it won't work on the phone, but the point is to demonstrate that the changed kernel config isn't the problem, and to have a baseline for comparison: mkdir cm cd cm repo init -u git://github.com/CyanogenMod/android.git -b cm-10.1 repo sync breakfast galaxysmtd nano -w .repo/local_manifests/roomservice.xml --- <?xml version="1.0" encoding="UTF-8"?> <manifest> <project name="CyanogenMod/android_device_samsung_galaxysmtd" path="device/samsung/galaxysmtd" remote="github" /> <project name="CyanogenMod/android_packages_apps_SamsungServiceMode" path="packages/apps/SamsungServiceMode" remote="gith$ <project name="CyanogenMod/android_device_samsung_aries-common" path="device/samsung/aries-common" remote="github" /> <project name="ali1234/android_kernel_samsung_aries" path="kernel/samsung/aries" remote="github" revision="saucy" /> <project name="CyanogenMod/android_hardware_samsung" path="hardware/samsung" remote="github" /> </manifest> --- repo sync cd devices/samsung/galaxysmtd ./extract-files.sh cd - cd vendor/cm ./get-prebuilts cd - brunch galaxysmtd The kernel files are now at out/target/product/galaxysmtd and out/target/product/galaxysmtd/obj/KERNEL_OBJ Take note of the sizes! Now build Ubuntu Touch with the same kernel source. Some patches are needed in other repos for this but again I already put them online: Ubuntu Touch: phablet-dev-bootstrap phablet cd phablet repo init -b phablet-saucy breakfast galaxysmtd nano -w .repo/local_manifests/roomservice.xml --- <?xml version="1.0" encoding="UTF-8"?> <manifest> <project name="CyanogenMod/android_device_samsung_galaxysmtd" path="device/samsung/galaxysmtd" remote="github" /> <project name="CyanogenMod/android_packages_apps_SamsungServiceMode" path="packages/apps/SamsungServiceMode" remote="gith$ <project name="ali1234/android_device_samsung_aries-common" path="device/samsung/aries-common" remote="github" revision="saucy" /> <project name="ali1234/android_kernel_samsung_aries" path="kernel/samsung/aries" remote="github" revision="saucy" /> <project name="ali1234/android_hardware_samsung" path="hardware/samsung" remote="github" revision="saucy" /> </manifest> --- repo sync cd devices/samsung/galaxysmtd ./extract-files.sh cd - brunch galaxysmtd This will fail with "no rule to make target android-boot.img" To get around this error, edit device/samsung/aries-common/shbootimg.mk and change "boot.img" to "android-boot.img" Now the build will fail because the "kernel" is huge. So now the question is, why is the same kernel source, same .config, same compiler producing two different kernels? al@al-desktop:~/Source/ubuntu-touch$ ls -l cm/out/target/product/galaxysmtd/obj/KERNEL_OBJ/arch/arm/boot/zImage -rwxrwxr-x 1 al al 6253960 Aug 2 15:31 cm/out/target/product/galaxysmtd/obj/KERNEL_OBJ/arch/arm/boot/zImage al@al-desktop:~/Source/ubuntu-touch$ ls -l phablet/out/target/product/galaxysmtd/obj/KERNEL_OBJ/arch/arm/boot/zImage -rwxrwxr-x 1 al al 8469884 Aug 2 18:35 phablet/out/target/product/galaxysmtd/obj/KERNEL_OBJ/arch/arm/boot/zImage 8469884 - 6253960 = 2215924 bytes difference The latter is much larger. Ok, let's look at the System.map to see why: al@al-desktop:~/Source/ubuntu-touch$ diff -y cm/out/target/product/galaxysmtd/obj/KERNEL_OBJ/System.map phablet/out/target/product/galaxysmtd/obj/KERNEL_OBJ/System.map | grep -C 4 \| | head -n 10 c002d4c8 T __initramfs_start c002d4c8 T __initramfs_start c002d4c8 t __irf_start c002d4c8 t __irf_start c002d4c8 T __security_initcall_end c002d4c8 T __security_initcall_end c002d4c8 T __security_initcall_start c002d4c8 T __security_initcall_start c04bb4c8 T __initramfs_size | c06ad4c8 T __initramfs_size c04bb4c8 t __irf_end | c06ad4c8 t __irf_end c04bb4d0 t kthreadd_done | c06ad4d0 t kthreadd_done c04bb4dc t done.29697 | c06ad4dc t done.29697 c04bb4e0 t tmp_cmdline.29698 | c06ad4e0 t tmp_cmdline.29698 c04bb8e0 T boot_command_line | c06ad8e0 T boot_command_line Notice here that __irf_start is the same in both, but __irf_end is different. They match up with __initramfs_start and __initramfs_size. 0xc06ad4c8 - 0xc04bb4c8 = 2039808 bytes difference 0xc04bb4c8 - 0xc002d4c8 = 4775936 bytes 0xc06ad4c8 - 0xc002d4c8 = 6815744 bytes from http://wiki.sourcemage.org/HowTo%282f%29Initramfs.html and http://comments.gmane.org/gmane.linux.kernel/1027539 this does indeed appear to be a built in initramfs inside the zImage. This is different to the way most android devices use mkbootimg to combine a zImage and ramdisk. In a real CyanogenMod rom for galaxysmtd, boot.img is not a mkbootimg image, nor is it it my earlier ubuntu-touch port. The offsets in System.map seem to be before compression, so perhaps this isn't the whole story, but for sure both kernels have an initramfs with different contents, and nothing else gets added later. I don't know where it comes from or how it ends up in the kernel though, at this point, but I have a theory: 2039808 bytes is almost the same as the difference between the original android ramdisk and the ubuntu touch ramdisk. Perhaps the android-boot.img actually contains the ubuntu-touch ramdisk by some accident? In which case, android-boot.img is already exactly what we want to boot from. I can't see any other reasonable explanation for why the kernel is bigger. The issue. Ubuntu Touch always wants the original android boot.img as android-boot.img and then it tries to build it's own boot.img using the kernel and ramdisk. But in this device, the kernel already contains a ramdisk (apparently). So then you get this error: ERROR: boot size (10670080) is 135.68% of limit (7864320) 10670080 is the 8469884 byte kernel + the ramdisk which is around 2M. Note that the kernel+initramfs combo is already too big alone at 8469884 bytes, but this is a separate problem if, as I suspect, the extra size is down to the ubuntu ramdisk being used instead of the original android one. -- Alistair Buxton a.j.bux...@gmail.com
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