基于tiny4412的Linux内核移植（支持device tree）（二）

作者信息

作者: 彭东林

邮箱：pengdonglin137@163.com

QQ：405728433

平台简介

开发板：tiny4412ADK + S700 + 4GB Flash

要移植的内核版本：Linux-4.4.0 （支持device tree）

u-boot版本：友善之臂自带的 U-Boot 2010.12 （为支持uImage启动，做了少许改动）

busybox版本：busybox 1.25

交叉编译工具链： arm-none-linux-gnueabi-gcc

      （gcc version 4.8.3 20140320 (prerelease) (Sourcery CodeBench Lite 2014.05-29)）

步骤

继续上文。

由于Linux-4.4.0对tiny4412已经有了很好的支持，所以留给我们的工作就很少了。

一、修改arch/arm/boot/dts/exynos4412-tiny4412.dts

diff --git a/arch/arm/boot/dts/exynos4412-tiny4412.dts b/arch/arm/boot/dts/exynos4412-tiny4412.dts
index 4840bbd..aeca42a 100644
--- a/arch/arm/boot/dts/exynos4412-tiny4412.dts
+++ b/arch/arm/boot/dts/exynos4412-tiny4412.dts
@@ -21,6 +21,7 @@

        chosen {
                stdout-path = &;serial_0;
+               bootargs = "root=/dev/ram0 rw rootfstype=ext4 console=ttySAC0,115200 init=/linuxrc earlyprintk";
        };

        memory {
@@ -78,7 +79,7 @@
        bus-width = <;4>;
        pinctrl-0 = <;&sd2_clk &sd2_cmd &sd2_cd &sd2_bus4>;
        pinctrl-names = "default";
-       status = "okay";
+       status = "disabled";
 };

 &;serial_0 {

这里关键的一点是在chosen中增加了bootargs的设置，上面设置bootargs表示的意思是：根文件系统是ramdisk，可读写，文件系统类型是ext4格式，串口终端使用ttySAC0，波特率是115200，earlyprintk用于打印内核启动早期的一些log，它会把printk的信息打印到一个叫做bootconsole的终端上，在真正的console注册后，bootconsole会被disable掉，要想使用earlyprintk，需要在内核中做相关的配置，这个下面再说。bootargs的设置很灵活，既可以在内核的设备树中设置，也可以在u-boot中设置，需要注意的是：如果在u-boot中设置了bootargs的话，在bootm的时候u-boot会用自己的bootargs来覆盖设备树里的bootargs( do_bootm_linux -> bootm_linux_fdt -> fdt_chosen)。还有一点是把SD卡控制器2给禁掉了，目前SD控制器的初始化还有些问题，会导致内核挂掉，这个以后再解决，因为我们将来先用ramdisk做根文件系统，跟eMMC和SD卡都没有关系。

二、制作ramdisk根文件系统

1、制作ramdisk，首先需要下载busybox的代码，可以从https://busybox.net/downloads/下载，然后编译出根文件系统，具体过程我这里就不写了，网上有很多这方面的资料。我已经制作好了一个可用了文件系统，可以从下面的地址处下载：

http://files.cnblogs.com/files/pengdonglin137/rootfs.tar.gz

下载完成后，解压缩，开始制作ramdisk，制作的过程我写了一个脚本 mk_ramdisk.sh

#!/bin/bash

rm -rf ramdisk*

sudo dd if=/dev/zero of=ramdisk bs=1k count=8192

sudo mkfs.ext4 -F ramdisk

sudo mkdir -p ./initrd
sudo mount -t ext4 ramdisk ./initrd

sudo cp rootfs/* ./initrd -raf

sudo mknod initrd/dev/console c 5 1
sudo mknod initrd/dev/null c 1 3

sudo umount ./initrd

sudo gzip --best -c ramdisk >; ramdisk.gz

sudo mkimage -n "ramdisk" -A arm -O linux -T ramdisk -C gzip -d ramdisk.gz ramdisk.img

最后生成的ramdisk.img就是我们需要的，在上面的脚本中生成的ramdisk镜像也可以作为ramdisk使用，用法下面再说。

下面的链接是一个已经制作好的ramdisk镜像，解压后即可使用：

http://files.cnblogs.com/files/pengdonglin137/ramdisk.zip

2、配置内核，支持ramdisk

make menuconfig
File systems --->;
    <*> Second extended fs support
Device Drivers
    SCSI device support --->;
        <*> SCSI disk support
    Block devices --->;
        <*>RAM block device support
        (16)Default number of RAM disks
        (8192) Default RAM disk size (kbytes) (修改为8M)
General setup --->;
    [*] Initial RAM filesystem and RAM disk (initramfs/initrd) support

这个exynos的默认配置就已经支持了。

3、配置内核，使其支持tmpfs

$ make menuconfig
File systems --->;
    Pseudo filesystems --->
        [*] Virtual memory file system support (former shm fs)
        [*] Tmpfs POSIX Access Control Lists

这个exynos的默认配置也已经支持了。

三、编译内核

1、首先要设置使用的交叉编译工具链

diff --git a/Makefile b/Makefile
index 70dea02..5d96411 100644
--- a/Makefile
+++ b/Makefile
@@ -248,8 +248,8 @@ SUBARCH := $(shell uname -m | sed -e s/i.86/x86/ -e s/x86_64/x86/
 # "make" in the configured kernel build directory always uses that.
 # Default value for CROSS_COMPILE is not to prefix executables
 # Note: Some architectures assign CROSS_COMPILE in their arch/*/Makefile
-ARCH           ?= $(SUBARCH)
-CROSS_COMPILE  ?= $(CONFIG_CROSS_COMPILE:"%"=%)
+ARCH           ?= arm
+CROSS_COMPILE  ?= /root/tiny4412_android5/SysPort/cross_compile/arm-2014.05/bin/arm-none-linux-gnueabi-

2、编译

make exynos_defconfig
make uImage LOADADDR=0x40008000 -j2

生成的uImage在arch/arm/boot下。 

四、编译设备树

make dtbs

然后在 arch/arm/boot/dts/会生成tiny4412上用的设备树镜像文件exynos4412-tiny4412.dtb。

五、测试

由于tiny4412的u-boot目前还不支持usb网卡，只能使用dnw来下载，并且tiny4412的u-boot中已经自带了dnw命令了。开发机上运行的dnw的代码可以到下面的链接下载：

http://files.cnblogs.com/files/pengdonglin137/dnw.tar.gz

下载完成后解压，在压缩包里已经有一个编译好的dnw可执行程序。也可执行make，会自动编译生成一个dnw可执行程序，要编译的话，机器上要安装usb相关的库，安装命令如下：

sudo  apt-get install libusb-dev

有了dnw，下面开始测试。

• 启动开发板，进入u-boot命令模式；
• 下载uImage

在u-boot里执行下载uImage的命令: dnw 0x40600000   (这个地址不唯一)

在开发机中执行：dnw arch/arm/boot/uImage

• 下载ramdisk

在u-boot里执行下载uImage的命令: dnw 0x41000000   (这个地址不唯一)

在开发机中执行：dnw ramdisk.img

• 下载设备树镜像

在u-boot里执行下载uImage的命令: dnw 0x42000000   (这个地址不唯一)

在开发机中执行：dnw arch/arm/boot/dts/exynos4412-tiny4412.dtb

• 启动内核

使用bootm启动内核：bootm 0x40600000 0x41000000 0x42000000

下面是完整的启动log：

U-Boot 2010.12-00000-gb391276-dirty (Jan 17 2016 - 06:03:22) for TINY4412


CPU:    S5PC220 [Samsung SOC on SMP Platform Base on ARM CortexA9]
        APLL = 1400MHz, MPLL = 800MHz

Board:  TINY4412
DRAM:   1023 MiB

vdd_arm: 1.2
vdd_int: 1.0
vdd_mif: 1.1

BL1 version:  N/A (TrustZone Enabled BSP)


Checking Boot Mode ... SDMMC
REVISION: 1.1
MMC Device 0: 3803 MB
MMC Device 1: 3728 MB
MMC Device 2: N/A
*** Warning - using default environment

Net:    No ethernet found.
Hit any key to stop autoboot:  0 
TINY4412 # dnw 0x41000000
OTG cable Connected!
Now, Waiting for DNW to transmit data
Download Done!! Download Address: 0x41000000, Download Filesize:0x27752e
Checksum is being calculated...
Checksum O.K.
TINY4412 # dnw 0x42000000
OTG cable Connected!
Now, Waiting for DNW to transmit data
Download Done!! Download Address: 0x42000000, Download Filesize:0xa53a
Checksum is being calculated.
Checksum O.K.
TINY4412 # dnw 0x40600000
OTG cable Connected!
Now, Waiting for DNW to transmit data
Download Done!! Download Address: 0x40600000, Download Filesize:0x43b5d0
Checksum is being calculated.....
Checksum O.K.
TINY4412 # bootm 0x40600000 0x41000000 0x42000000
## Booting kernel from Legacy Image at 40600000 ...
   Image Name:   Linux-4.4.0-gbd49c0f-dirty
   Image Type:   ARM Linux Kernel Image (uncompressed)
   Data Size:    4437392 Bytes = 4333 KiB
   Load Address: 40008000
   Entry Point:  40008000
   Verifying Checksum ... OK
## Loading init Ramdisk from Legacy Image at 41000000 ...
   Image Name:   ramdisk
   Image Type:   ARM Linux RAMDisk Image (gzip compressed)
   Data Size:    2585838 Bytes = 2525 KiB
   Load Address: 00000000
   Entry Point:  00000000
   Verifying Checksum ... OK
## Flattened Device Tree blob at 42000000
   Booting using the fdt blob at 0x42000000
   Loading Kernel Image ... OK
OK
## Loading init Ramdisk from Legacy Image at 41000000 ...
   Image Name:   ramdisk
   Image Type:   ARM Linux RAMDisk Image (gzip compressed)
   Data Size:    2585838 Bytes = 2525 KiB
   Load Address: 00000000
   Entry Point:  00000000
   Verifying Checksum ... OK
   Loading Ramdisk to 43a84000, end 43cfb4ee ... OK
   Loading Device Tree to 413f2000, end 413ff539 ... OK

Starting kernel ...

Uncompressing Linux... done, booting the kernel.
[    0.000000] Booting Linux on physical CPU 0xa00
[    0.000000] Linux version 4.4.0-gbd49c0f-dirty (root@ubuntu) (gcc version 4.8.3 20140320 (prerelease) (Sourcery CodeBench Lite 2014.05-29) ) #24 SMP PREEMPT Tue Jan 19 05:39:48 PST 2016
[    0.000000] CPU: ARMv7 Processor [413fc090] revision 0 (ARMv7), cr=10c5387d
[    0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
[    0.000000] Machine model: FriendlyARM TINY4412 board based on Exynos4412
[    0.000000] bootconsole [earlycon0] enabled
[    0.000000] cma: Reserved 64 MiB at 0x7bc00000
[    0.000000] Memory policy: Data cache writealloc
[    0.000000] Samsung CPU ID: 0xe4412011
[    0.000000] PERCPU: Embedded 12 pages/cpu @ef79b000 s18816 r8192 d22144 u49152
[    0.000000] Built 1 zonelists in Zone order, mobility grouping on.  Total pages: 260352
[    0.000000] Kernel command line: root=/dev/ram0 rw rootfstype=ext4 console=ttySAC0,115200 init=/linuxrc earlyprintk
[    0.000000] PID hash table entries: 4096 (order: 2, 16384 bytes)
[    0.000000] Dentry cache hash table entries: 131072 (order: 7, 524288 bytes)
[    0.000000] Inode-cache hash table entries: 65536 (order: 6, 262144 bytes)
[    0.000000] Memory: 960832K/1047552K available (5863K kernel code, 292K rwdata, 2284K rodata, 440K init, 315K bss, 21184K reserved, 65536K cma-reserved, 195584K highmem)
[    0.000000] Virtual kernel memory layout:
[    0.000000]     vector  : 0xffff0000 - 0xffff1000   (   4 kB)
[    0.000000]     fixmap  : 0xffc00000 - 0xfff00000   (3072 kB)
[    0.000000]     vmalloc : 0xf0800000 - 0xff800000   ( 240 MB)
[    0.000000]     lowmem  : 0xc0000000 - 0xf0000000   ( 768 MB)
[    0.000000]     pkmap   : 0xbfe00000 - 0xc0000000   (   2 MB)
[    0.000000]     modules : 0xbf000000 - 0xbfe00000   (  14 MB)
[    0.000000]       .text : 0xc0008000 - 0xc07fd188   (8149 kB)
[    0.000000]       .init : 0xc07fe000 - 0xc086c000   ( 440 kB)
[    0.000000]       .data : 0xc086c000 - 0xc08b52f0   ( 293 kB)
[    0.000000]        .bss : 0xc08b8000 - 0xc0906d28   ( 316 kB)
[    0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=4, Nodes=1
[    0.000000] Preemptible hierarchical RCU implementation.
[    0.000000]  Build-time adjustment of leaf fanout to 32.
[    0.000000]  RCU restricting CPUs from NR_CPUS=8 to nr_cpu_ids=4.
[    0.000000] RCU: Adjusting geometry for rcu_fanout_leaf=32, nr_cpu_ids=4
[    0.000000] NR_IRQS:16 nr_irqs:16 16
[    0.000000] GIC physical location is 0x10490000
[    0.000000] L2C: platform modifies aux control register: 0x02070000 ->; 0x3e470001
[    0.000000] L2C: platform provided aux values permit register corruption.
[    0.000000] L2C: DT/platform modifies aux control register: 0x02070000 ->; 0x3e470001
[    0.000000] L2C-310 enabling early BRESP for Cortex-A9
[    0.000000] L2C-310: enabling full line of zeros but not enabled in Cortex-A9
[    0.000000] L2C-310 dynamic clock gating enabled, standby mode enabled
[    0.000000] L2C-310 cache controller enabled, 16 ways, 1024 kB
[    0.000000] L2C-310: CACHE_ID 0x4100c4c8, AUX_CTRL 0x4e470001
[    0.000000] Exynos4x12 clocks: sclk_apll = 466666667, sclk_mpll = 800000000
[    0.000000]  sclk_epll = 96000000, sclk_vpll = 108000000, arm_clk = 1400000000
[    0.000000] Switching to timer-based delay loop, resolution 41ns
[    0.000000] clocksource: mct-frc: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 79635851949 ns
[    0.000003] sched_clock: 32 bits at 24MHz, resolution 41ns, wraps every 89478484971ns
[    0.008035] Console: colour dummy device 80x30
[    0.012425] Calibrating delay loop (skipped), value calculated using timer frequency.. 48.00 BogoMIPS (lpj=120000)
[    0.022827] pid_max: default: 32768 minimum: 301
[    0.027579] Mount-cache hash table entries: 2048 (order: 1, 8192 bytes)
[    0.034206] Mountpoint-cache hash table entries: 2048 (order: 1, 8192 bytes)
[    0.041686] CPU: Testing write buffer coherency: ok
[    0.046640] CPU0: thread -1, cpu 0, socket 10, mpidr 80000a00
[    0.052536] Setting up static identity map for 0x400082c0 - 0x40008318
[    0.099784] CPU1: thread -1, cpu 1, socket 10, mpidr 80000a01
[    0.114774] CPU2: thread -1, cpu 2, socket 10, mpidr 80000a02
[    0.129775] CPU3: thread -1, cpu 3, socket 10, mpidr 80000a03
[    0.129815] Brought up 4 CPUs
[    0.150143] SMP: Total of 4 processors activated (192.00 BogoMIPS).
[    0.156477] CPU: All CPU(s) started in SVC mode.
[    0.161676] devtmpfs: initialized
[    0.173957] VFP support v0.3: implementor 41 architecture 3 part 30 variant 9 rev 4
[    0.181783] lcd0-power-domain@10023C80 has as child subdomain: tv-power-domain@10023C20.
[    0.190155] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 9556302231375000 ns
[    0.201755] pinctrl core: initialized pinctrl subsystem
[    0.207668] NET: Registered protocol family 16
[    0.213539] DMA: preallocated 256 KiB pool for atomic coherent allocations
[    0.234740] cpuidle: using governor ladder
[    0.249735] cpuidle: using governor menu
[    0.254286] exynos-audss-clk 3810000.clock-controller: setup completed
[    0.306823] SCSI subsystem initialized
[    0.310855] usbcore: registered new interface driver usbfs
[    0.316329] usbcore: registered new interface driver hub
[    0.321714] usbcore: registered new device driver usb
[    0.327898] Advanced Linux Sound Architecture Driver Initialized.
[    0.335087] clocksource: Switched to clocksource mct-frc
[    0.349988] missing cooling_device property
[    0.354099] failed to build thermal zone cpu-thermal: -2
[    0.359566] NET: Registered protocol family 2
[    0.364266] TCP established hash table entries: 8192 (order: 3, 32768 bytes)
[    0.371286] TCP bind hash table entries: 8192 (order: 5, 163840 bytes)
[    0.377936] TCP: Hash tables configured (established 8192 bind 8192)
[    0.384305] UDP hash table entries: 512 (order: 2, 24576 bytes)
[    0.390258] UDP-Lite hash table entries: 512 (order: 2, 24576 bytes)
[    0.396795] NET: Registered protocol family 1
[    0.401289] RPC: Registered named UNIX socket transport module.
[    0.407131] RPC: Registered udp transport module.
[    0.411902] RPC: Registered tcp transport module.
[    0.416674] RPC: Registered tcp NFSv4.1 backchannel transport module.
[    0.423325] Trying to unpack rootfs image as initramfs...
[    0.429054] rootfs image is not initramfs (no cpio magic); looks like an initrd
[    0.442728] Freeing initrd memory: 2528K (c3a84000 - c3cfc000)
[    0.449900] futex hash table entries: 1024 (order: 4, 65536 bytes)
[    0.465272] romfs: ROMFS MTD (C) 2007 Red Hat, Inc.
[    0.470817] bounce: pool size: 64 pages
[    0.474564] io scheduler noop registered
[    0.478570] io scheduler deadline registered
[    0.483072] io scheduler cfq registered (default)
[    0.492532] dma-pl330 12680000.pdma: Loaded driver for PL330 DMAC-141330
[    0.499160] dma-pl330 12680000.pdma:         DBUFF-32x4bytes Num_Chans-8 Num_Peri-32 Num_Events-32
[    0.510651] dma-pl330 12690000.pdma: Loaded driver for PL330 DMAC-141330
[    0.517272] dma-pl330 12690000.pdma:         DBUFF-32x4bytes Num_Chans-8 Num_Peri-32 Num_Events-32
[    0.526575] dma-pl330 12850000.mdma: Loaded driver for PL330 DMAC-141330
[    0.533201] dma-pl330 12850000.mdma:         DBUFF-64x8bytes Num_Chans-8 Num_Peri-1 Num_Events-32
[    0.601269] Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled
[    0.608816] 13800000.serial: ttySAC0 at MMIO 0x13800000 (irq = 44, base_baud = 0) is a S3C6400/10
[    0.617669] console [ttySAC0] enabled
[    0.617669] console [ttySAC0] enabled
[    0.624994] bootconsole [earlycon0] disabled
[    0.624994] bootconsole [earlycon0] disabled
[    0.633916] 13810000.serial: ttySAC1 at MMIO 0x13810000 (irq = 45, base_baud = 0) is a S3C6400/10
[    0.634277] 13820000.serial: ttySAC2 at MMIO 0x13820000 (irq = 46, base_baud = 0) is a S3C6400/10
[    0.634631] 13830000.serial: ttySAC3 at MMIO 0x13830000 (irq = 47, base_baud = 0) is a S3C6400/10
[    0.639182] [drm] Initialized drm 1.1.0 20060810
[    0.652946] brd: module loaded
[    0.657821] loop: module loaded
[    0.658627] usbcore: registered new interface driver r8152
[    0.658763] usbcore: registered new interface driver asix
[    0.659855] usbcore: registered new interface driver ax88179_178a
[    0.665958] usbcore: registered new interface driver cdc_ether
[    0.671772] usbcore: registered new interface driver smsc75xx
[    0.677506] usbcore: registered new interface driver smsc95xx
[    0.683217] usbcore: registered new interface driver net1080
[    0.688858] usbcore: registered new interface driver cdc_subset
[    0.694760] usbcore: registered new interface driver zaurus
[    0.700345] usbcore: registered new interface driver cdc_ncm
[    0.706295] ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
[    0.712416] ehci-exynos: EHCI EXYNOS driver
[    0.716700] ohci_hcd: USB 1.1 'Open' Host Controller (OHCI) Driver
[    0.722742] ohci-exynos: OHCI EXYNOS driver
[    0.727264] usbcore: registered new interface driver usb-storage
[    0.733431] mousedev: PS/2 mouse device common for all mice
[    0.739205] s3c-rtc 10070000.rtc: failed to find rtc source clock
[    0.744539] s3c-rtc: probe of 10070000.rtc failed with error -2
[    0.750636] i2c /dev entries driver
[    0.755967] device-mapper: ioctl: 4.34.0-ioctl (2015-10-28) initialised: dm-devel@redhat.com
[    0.763141] sdhci: Secure Digital Host Controller Interface driver
[    0.768478] sdhci: Copyright(c) Pierre Ossman
[    0.772952] Synopsys Designware Multimedia Card Interface Driver
[    0.780793] usbcore: registered new interface driver usbhid
[    0.784347] usbhid: USB HID core driver
[    0.791116] NET: Registered protocol family 10
[    0.793128] sit: IPv6 over IPv4 tunneling driver
[    0.797746] NET: Registered protocol family 17
[    0.801655] NET: Registered protocol family 15
[   0.806225] Registering SWP/SWPB emulation handler
[    0.812058] hctosys: unable to open rtc device (rtc0)
[    0.827998] ALSA device list:
[    0.828035]   No soundcards found.
[    0.828678] RAMDISK: gzip image found at block 0
[    0.970206] EXT4-fs (ram0): mounted filesystem wirdered data mode. Opts: (null)
[    0.970301] VFS: Mounted root (ext4 filesystem) on device 1:0.
[    0.970419] devtmpfs: mounted
[    0.970694] Freeing unused kernel memory: 440K (c07fe000 - c086c000)

Please press Enter to activate this console. 
[root@tiny4412 ]# 

未完待续。