android kernel和标准linux kernel的区别
android kernel和标准linux kernel的区别
android kernel和标准linux kernel的区别
总的区别可以归纳如下：
ARCH -- 这是Android修改了arch/arm下面的一些档案：
arch/arm:
Chg: arch/arm/kernel/entry-armv.S
Chg: arch/arm/kernel/module.c
Chg: arch/arm/kernel/process.c
Chg: arch/arm/kernel/ptrace.c
Chg: arch/arm/kernel/setup.c
Chg: arch/arm/kernel/signal.c
Chg: arch/arm/kernel/traps.c
Chg: arch/arm/mm/cache-v6.S
Chg: arch/arm/vfp/entry.S
Chg: arch/arm/vfp/vfp.h
Chg: arch/arm/vfp/vfphw.S
Chg: arch/arm/vfp/vfpmodule.c
Goldfish -- 这是Android为了模拟器所开发的一个虚拟硬体平台。Goldfish执行arm926T指令（在2.6.29中，goldfish也支援ATMv7指令），但是在实际的装置中，该虚拟平台的档案不会被编译。
arch/arm/mach-goldfish:
New: arch/arm/mach-goldfish/audio.c
New: arch/arm/mach-goldfish/board-goldfish.c
New: arch/arm/mach-goldfish/pdev_bus.c
New: arch/arm/mach-goldfish/pm.c
New: arch/arm/mach-goldfish/switch.c
New: arch/arm/mach-goldfish/timer.c
YAFFS2 -- 和PC把档案储存在硬碟上不一样， 移动装置一般把Flash作为储存装置。尤其是NAND flash应用非常广泛（绝大多数手机用的都是NAND flash，三星的一些手机使用的是OneNAND）。NAND flash具有低成本和高密度的优点。
YAFFS2 是“Yet Another Flash File System, 2nd edition" 的简称。 它提供在Linux核心和NAND flash装置 之前高效率的介面。 YAFFS2并没有包含在标准的Linux核心中， Google把它新增到了Android的kernel
fs/yaffs2:
New: fs/yaffs2/devextras.h
New: fs/yaffs2/Kconfig
New: fs/yaffs2/Makefile
New: fs/yaffs2/moduleconfig.h
New: fs/yaffs2/yaffs_checkptrw.c
New: fs/yaffs2/yaffs_checkptrw.h
New: fs/yaffs2/yaffs_e.c
New: fs/yaffs2/yaffs_e.h
New: fs/yaffs2/yaffs_fs.c
New: fs/yaffs2/yaffs_getblockinfo.h
New: fs/yaffs2/yaffs_guts.c
New: fs/yaffs2/yaffs_guts.h
New: fs/yaffs2/yaffsinterface.h
New: fs/yaffs2/yaffs_mtdif1.c
New: fs/yaffs2/yaffs_mtdif1.h
New: fs/yaffs2/yaffs_mtdif2.c
New: fs/yaffs2/yaffs_mtdif2.h
New: fs/yaffs2/yaffs_mtdif.c
New: fs/yaffs2/yaffs_mtdif.h
New: fs/yaffs2/yaffs_nand.c
New: fs/yaffs2/yaffs_nandemul2k.h
New: fs/yaffs2/yaffs_nand.h
New: fs/yaffs2/yaffs_packedtags1.c
New: fs/yaffs2/yaffs_packedtags1.h
New: fs/yaffs2/yaffs_packedtags2.c
New: fs/yaffs2/yaffs_packedtags2.h
New: fs/yaffs2/yaffs_qsort.c
New: fs/yaffs2/yaffs_qsort.h
New: fs/yaffs2/yaffs_tagspat.c
New: fs/yaffs2/yaffs_tagspat.h
New: fs/yaffs2/yaffs_tagsvalidity.c
New: fs/yaffs2/yaffs_tagsvalidity.h
New: fs/yaffs2/yportenv.h
Bluetooth -- Google为Bluetooth打上了patch，fix了一些Bluetooth的bug
drivers/bluetooth:
Chg: drivers/bluetooth/bfu *** .c
Chg: drivers/bluetooth/bt3c_cs.c
Chg: drivers/bluetooth/btu *** .c
Chg: drivers/bluetooth/hci_h4.c
Chg: drivers/bluetooth/hci_ll.c
Scheduler -- 对于Scheduler的改变非常小，我对它并没有去研究。
Chg: kernel/sched.c
IPC Binder -- The IPC Binder is an Inter-Process Communication (IPC) mechani *** . It allows processes to provide services to other processes via a set of higher-level APIs than are available in standard Linux. An Inter search indicated that the Binder concept originated at Be, Inc., and then made its way into Palm's sofare, before Google wrote a new Binder for Android.
New: drivers/staging/android/binder.c
Low Memory Killer -- Android adds a low-memory killer that, each time it's called, scans the list of running Linux processes, and kills one. It was not clear in our cursory examination why Android adds a low-memory killer on of the already existing one in the standard Linux kernel.
New: drivers/staging/android/lowmemorykiller.c
Ashmem -- Ashmem is an Anonymous SHared MEMory system that adds interfaces so processes can share named blocks of memory. As an example, the system could use Ashmem to store icons, which multiple processes could then aess when drawing their UI. The advantage of Ashmem over traditional Linux shared memory is that it provides a means for the kernel to reclaim these shared memory blocks if they are not currently in use. If a process then tries to aess a shared memory block the kernel has freed, it will receive an error, and will then need to reallocate the block and reload the data.
New: mm/ashmem.c
RAM Console and Log Device -- To aid in debugging, Android adds the ability to store kernel log messages to a RAM buffer. Additionally, Android adds a separate logging module so that user processes can read and write user log messages.
New: drivers/staging/android/ram_console.c
Android Debug Bridge -- Debugging embedded devices can best be described as challenging. To make debugging easier, Google created the Android Debug Bridge (ADB), which is a protocol that runs over a USB link beeen a hardware device running Android and a developer writing applications on a desk PC.
drivers/u *** /gadget:
New: drivers/u *** /gadget/android.c
Chg: drivers/u *** /gadget/posite.c
Chg: drivers/u *** /gadget/f_acm.c
New: drivers/u *** /gadget/f_acm.h
New: drivers/u *** /gadget/f_adb.c
New: drivers/u *** /gadget/f_adb.h
New: drivers/u *** /gadget/f_mass_storage.c
New: drivers/u *** /gadget/f_mass_storage.h
Android also adds a new real-time clock, switch support, and timed GPIO support. We list the impacted files for these new modules at the end of this document.
Power Management -- Power management is one of the most difficult pieces to get right in mobile devices, so we split it out into a group separate from the other pieces. It's interesting to note that Google added a new power management system to Linux, rather than reuse what already existed. We list the impacted files at the end of this document.
kernel/power:
New: kernel/power/consoleearlysuspend.c
New: kernel/power/earlysuspend.c
New: kernel/power/fbearlysuspend.c
Chg: kernel/power/main.c
Chg: kernel/power/power.h
Chg: kernel/power/process.c
New: kernel/power/userwakelock.c
New: kernel/power/wakelock.c
Miscellaneous Changes -- In addition to the above, we found a number of changes that could best be described as, 'Miscellaneous.' Among other things, these changes include additional debugging support, keypad light controls, and management of TCP neorking.
(freedom_asic)
Android kernel是从linux kernel 修改过来的，大部分的核心没什么变化。Android厂商会定制原始码修改驱动 或者增加新的特性等。
