NUC980如何进行内核修改并进行烧录

106 阅读 0 评论 70 点赞

我是靠谱客的博主重要帆布鞋，这篇文章主要介绍NUC980如何进行内核修改并进行烧录，现在分享给大家，希望可以做个参考。

由于此处使用的为nor-flash，而且不适用RAMfs文件系统，因此配置内核为3MB大小，uboot为1MB大小，剩余的空间为文件系统空间，后续如果有需求再进行改动。
1、配置环境变量的文件系统，配置内容下：

复制代码

1
2
3
4
5
6
7
8
9
10
11
baudrate=115200
bootdelay=1
stderr=serial
stdin=serial
stdout=serial
setspi=sf probe 0 50000000  //配置SPI-flash读取速度为50M
loadkernel=sf read 0x7fc0 0x100000 0x300000 //从1M的地址空间读取3MB的数据到内存中
bootcmd=run setspi;run loadkernel;bootm 0x7fc0 //load内核文件，直接启动
bootargs=noinitrd root=/dev/mtdblock2 rw rootfstype=jffs2 console=ttyS0,115200n8 rdinit=/sbin/init mem=64M mtdparts=nor0:0x100000@0x0(u-boot),0x300000@0x100000(kernel),-(user)；//mtdparts 用于传递参数到内核当中
环境变量直接烧录到0x80000位置即可，使用nuwriter烧录模式即可。

这里还是要说几句，在进行u-boot移植时，有人喜欢将MTD分区表设置好，然后使用uboot指令进行相关的文件操作，个人感觉是没有必要的，uboot在实际的开发工作中，占比比较小，正常操作应该直接将参数传递到内核中，由内核进行MTD分区，然后通过启动文件系统即可，这样启动的速度是最快，u-boot做MTD只是用于内存操作时比较方便，其他没什么作用，而且设置错误也会出现编译问题，因此尽量先不要将MTD编译到u-boot当中，直接使用厂家的uboot即可。
为保证移植成功，要修改内核的mtd分区，通过修改源代码的方式进行修改，主要就是修改mtd的配置，直接在内核的文件夹输入

复制代码

1
2
vim arch/arm/mach-nuc980/dev.c

将其修改为如下数值，然后保存，后续配置后进行make即可。

复制代码

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
static struct mtd_partition nuc980_qspi0_flash_partitions[] = {
#ifdef CONFIG_BOARD_ETH2UART
        {
                .name = "lighttpd",
                .size = 0x0200000,
                .offset = 0x0C00000,
        },
#else
        {
                .name = "u-boot",
                .size = 0x0100000,
                .offset = 0,
        },
        {
                .name = "kernel",
                .size = 0x0300000,
                .offset = 0x100000,
        },
        {
                .name = "user",
                .size = 0xc00000,
                .offset = 0x0400000,
        },

注意在内核进行配置的过程中使用make nuc980_defconfig，这样可以将内核的标准配置导出来，如果使用ETH2UART的config文件，则不会调用此处修改的mtd分区，可以在内核的实际打印信息中看到。
这样制作空间划分如下

Uboot 1M空间
内核 3M空间
用户 12M空间

如果没有增加非常多的服务，那么这样的划分是没有问题的，内核的裁剪一定要到位，不必要的服务必须全部切掉，保证内核足够精简，user的空间其实也可以划分为两部分，使用前面7M用于挂在文件系统，后面用于挂在其他文件，保证加载文件系统的速度。
2、内核需增加MTD相关选项，SPI-flash相关选项，并将所有不必要的选项都关闭，如关闭USB，关闭网络等，都是没有必要的程序，删除之后就可以进行编译下载了，并取消使用RAM加载文件系统的选项，编译完成的内核代码一般都在2M以内，根据上述的分配，内核空间有3M，完全满足需求，直接将代码下载到0x100000位置即可。
3、实际的内核裁剪比较复杂，选线比较多，如果有不清楚的选项可以先进行搜索，确认其功能然后进行修改，在修改的过程中，应该先修改硬件相关的驱动文件，然后修改mtd，然后修改文件系统等，因为各个选项都是关联的，如果驱动没有被选中，那么在工作的过程中就会出现问题，对于没有选择的硬件驱动，应该尽量将对应的应用驱动删除，如没有选用nand相关的硬件驱动，则应该删除nand相关的文件系统支持，否则编译就会出错。
进行裁剪后加载完成的界面如图

复制代码

U-Boot 2016.11-g3ac85d0-dirty (Aug 17 2019 - 15:51:52 +0800)
    
    CPU: NUC980
    Board: NUC980
    DRAM:  64 MiB
    SF: Detected W25Q128BV with page size 256 Bytes, erase size 64 KiB, total 16 MiB
    In:    serial
    Out:   serial
    Err:   serial
    Net:   Net Initialization Skipped
    No ethernet found.
    Hit any key to stop autoboot:  0 
    SF: Detected W25Q128BV with page size 256 Bytes, erase size 64 KiB, total 16 MiB
    device 0 offset 0x100000, size 0x300000
    SF: 3145728 bytes @ 0x100000 Read: OK
    ## Booting kernel from Legacy Image at 00007fc0 ...
       Image Name:   
       Image Type:   ARM Linux Kernel Image (uncompressed)
       Data Size:    1579528 Bytes = 1.5 MiB
       Load Address: 00007fc0
       Entry Point:  00008000
       Verifying Checksum ... OK
       Loading Kernel Image ... OK
    
    Starting kernel ...
    
    SF: Detected W25Q128BV with page size 256 Bytes, erase size 64 KiB, total 16 MiB
    SF: Deviceting Linux on physical CPU 0x0
    Linux version 4.4.179 (root@dongwb) (gcc version 4.8.4 (GCC) ) #27 PREEMPT Thu Aug 22 00:01:15 CST 2019
    CPU: ARM926EJ-S [41069265] revision 5 (ARMv5TEJ), cr=0005317f
    CPU: VIVT data cache, VIVT instruction cache
    Machine: NUC980
    Memory policy: Data cache writeback
    Built 1 zonelists in Zone order, mobility grouping on.  Total pages: 16256
    Kernel command line: noinitrd root=/dev/mtdblock2 rw rootfstype=jffs2 console=ttyS0,115200n8 rdinit=/sbin/init mem=64M mtdparts=nor0:0x100000@0x0(u-boot),0x300000@0x100000(kernel),-(user)PID hash table entries: 256 (order: -2, 1024 bytes)
    Dentry cache hash table entries: 8192 (order: 3, 32768 bytes)
    Inode-cache hash table entries: 4096 (order: 2, 16384 bytes)
    Memory: 61428K/65536K available (2162K kernel code, 199K rwdata, 768K rodata, 124K init, 195K bss, 4108K reserved, 0K cma-reserved)
    Virtual kernel memory layout:
        vector  : 0xffff0000 - 0xffff1000   (   4 kB)
        fixmap  : 0xffc00000 - 0xfff00000   (3072 kB)
        vmalloc : 0xc4800000 - 0xff800000   ( 944 MB)
        lowmem  : 0xc0000000 - 0xc4000000   (  64 MB)
        modules : 0xbf000000 - 0xc0000000   (  16 MB)
          .text : 0xc0008000 - 0xc02e4ecc   (2932 kB)
          .init : 0xc02e5000 - 0xc0304000   ( 124 kB)
          .data : 0xc0304000 - 0xc0335f00   ( 200 kB)
           .bss : 0xc0335f00 - 0xc0366e78   ( 196 kB)
    SLUB: HWalign=32, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
    Preemptible hierarchical RCU implementation.
            Build-time adjustment of leaf fanout to 32.
    NR_IRQS:545
    clocksource: nuc980-timer5: mask: 0xffffff max_cycles: 0xffffff, max_idle_ns: 62215505635 ns
    sched_clock: 32 bits at 100 Hz, resolution 10000000ns, wraps every 21474836475000000ns
    Console: colour dummy device 80x30
    console [ttyS0] enabled
    Calibrating delay loop... 148.88 BogoMIPS (lpj=744448)
    pid_max: default: 32768 minimum: 301
    Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
    Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
    CPU: Testing write buffer coherency: ok
    Setting up static identity map for 0x8400 - 0x843c
    devtmpfs: initialized
    clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
    futex hash table entries: 256 (order: -1, 3072 bytes)
    pinctrl core: initialized pinctrl subsystem
    DMA: preallocated 256 KiB pool for atomic coherent allocations
    SCSI subsystem initialized
    clocksource: Switched to clocksource nuc980-timer5
    NetWinder Floating Point Emulator V0.97 (double precision)
    jffs2: version 2.2. (NAND) (SUMMARY)  © 2001-2006 Red Hat, Inc.
    Block layer SCSI generic (bsg) driver version 0.4 loaded (major 254)
    io scheduler noop registered (default)
    nuc980_gpio_probe - pdev = nuc980-gpio
    nuc980_dma_probe - pdev = nuc980-dma
    nuc980-dma nuc980-dma: NUC980 DMA ready
    nuc980-uart.0: ttyS0 at I/O 0x0 (irq = 36, base_baud = 750000) is a NUC980
    brd: module loaded
    RX nuc980_qspi0_probe: dma0chan0 module removed
    TX nuc980_qspi0_probe: dma0chan1 module removed
    m25p80 spi0.0: found w25q128, expected mx66l51235l
    m25p80 spi0.0: w25q128 (16384 Kbytes)
    Creating 3 MTD partitions on "m25p80":
    0x000000000000-0x000000100000 : "u-boot"
    0x000000100000-0x000000400000 : "kernel"
    0x000000400000-0x000001000000 : "user"
    RX nuc980_spi0_probe: dma0chan2 module removed
    TX nuc980_spi0_probe: dma0chan3 module removed
    m25p80 spi1.0: unrecognized JEDEC id bytes: ff, ff, ff
    m25p80: probe of spi1.0 failed with error -2
    VFS: Mounted root (jffs2 filesystem) on device 31:2.
    devtmpfs: mounted
    Freeing unused kernel memory: 124K
    [Mount JFFS2]: /dev/mtdblock2 --> /mnt/mtdblock2
    
    BusyBox v1.22.1 (2016-02-03 14:11:04 CST) built-in shell (ash)
    Enter 'help' for a list of built-in commands.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
U-Boot 2016.11-g3ac85d0-dirty (Aug 17 2019 - 15:51:52 +0800)
    
    CPU: NUC980
    Board: NUC980
    DRAM:  64 MiB
    SF: Detected W25Q128BV with page size 256 Bytes, erase size 64 KiB, total 16 MiB
    In:    serial
    Out:   serial
    Err:   serial
    Net:   Net Initialization Skipped
    No ethernet found.
    Hit any key to stop autoboot:  0 
    SF: Detected W25Q128BV with page size 256 Bytes, erase size 64 KiB, total 16 MiB
    device 0 offset 0x100000, size 0x300000
    SF: 3145728 bytes @ 0x100000 Read: OK
    ## Booting kernel from Legacy Image at 00007fc0 ...
       Image Name:   
       Image Type:   ARM Linux Kernel Image (uncompressed)
       Data Size:    1579528 Bytes = 1.5 MiB
       Load Address: 00007fc0
       Entry Point:  00008000
       Verifying Checksum ... OK
       Loading Kernel Image ... OK
    
    Starting kernel ...
    
    SF: Detected W25Q128BV with page size 256 Bytes, erase size 64 KiB, total 16 MiB
    SF: Deviceting Linux on physical CPU 0x0
    Linux version 4.4.179 (root@dongwb) (gcc version 4.8.4 (GCC) ) #27 PREEMPT Thu Aug 22 00:01:15 CST 2019
    CPU: ARM926EJ-S [41069265] revision 5 (ARMv5TEJ), cr=0005317f
    CPU: VIVT data cache, VIVT instruction cache
    Machine: NUC980
    Memory policy: Data cache writeback
    Built 1 zonelists in Zone order, mobility grouping on.  Total pages: 16256
    Kernel command line: noinitrd root=/dev/mtdblock2 rw rootfstype=jffs2 console=ttyS0,115200n8 rdinit=/sbin/init mem=64M mtdparts=nor0:0x100000@0x0(u-boot),0x300000@0x100000(kernel),-(user)PID hash table entries: 256 (order: -2, 1024 bytes)
    Dentry cache hash table entries: 8192 (order: 3, 32768 bytes)
    Inode-cache hash table entries: 4096 (order: 2, 16384 bytes)
    Memory: 61428K/65536K available (2162K kernel code, 199K rwdata, 768K rodata, 124K init, 195K bss, 4108K reserved, 0K cma-reserved)
    Virtual kernel memory layout:
        vector  : 0xffff0000 - 0xffff1000   (   4 kB)
        fixmap  : 0xffc00000 - 0xfff00000   (3072 kB)
        vmalloc : 0xc4800000 - 0xff800000   ( 944 MB)
        lowmem  : 0xc0000000 - 0xc4000000   (  64 MB)
        modules : 0xbf000000 - 0xc0000000   (  16 MB)
          .text : 0xc0008000 - 0xc02e4ecc   (2932 kB)
          .init : 0xc02e5000 - 0xc0304000   ( 124 kB)
          .data : 0xc0304000 - 0xc0335f00   ( 200 kB)
           .bss : 0xc0335f00 - 0xc0366e78   ( 196 kB)
    SLUB: HWalign=32, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
    Preemptible hierarchical RCU implementation.
            Build-time adjustment of leaf fanout to 32.
    NR_IRQS:545
    clocksource: nuc980-timer5: mask: 0xffffff max_cycles: 0xffffff, max_idle_ns: 62215505635 ns
    sched_clock: 32 bits at 100 Hz, resolution 10000000ns, wraps every 21474836475000000ns
    Console: colour dummy device 80x30
    console [ttyS0] enabled
    Calibrating delay loop... 148.88 BogoMIPS (lpj=744448)
    pid_max: default: 32768 minimum: 301
    Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
    Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
    CPU: Testing write buffer coherency: ok
    Setting up static identity map for 0x8400 - 0x843c
    devtmpfs: initialized
    clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
    futex hash table entries: 256 (order: -1, 3072 bytes)
    pinctrl core: initialized pinctrl subsystem
    DMA: preallocated 256 KiB pool for atomic coherent allocations
    SCSI subsystem initialized
    clocksource: Switched to clocksource nuc980-timer5
    NetWinder Floating Point Emulator V0.97 (double precision)
    jffs2: version 2.2. (NAND) (SUMMARY)  © 2001-2006 Red Hat, Inc.
    Block layer SCSI generic (bsg) driver version 0.4 loaded (major 254)
    io scheduler noop registered (default)
    nuc980_gpio_probe - pdev = nuc980-gpio
    nuc980_dma_probe - pdev = nuc980-dma
    nuc980-dma nuc980-dma: NUC980 DMA ready
    nuc980-uart.0: ttyS0 at I/O 0x0 (irq = 36, base_baud = 750000) is a NUC980
    brd: module loaded
    RX nuc980_qspi0_probe: dma0chan0 module removed
    TX nuc980_qspi0_probe: dma0chan1 module removed
    m25p80 spi0.0: found w25q128, expected mx66l51235l
    m25p80 spi0.0: w25q128 (16384 Kbytes)
    Creating 3 MTD partitions on "m25p80":
    0x000000000000-0x000000100000 : "u-boot"
    0x000000100000-0x000000400000 : "kernel"
    0x000000400000-0x000001000000 : "user"
    RX nuc980_spi0_probe: dma0chan2 module removed
    TX nuc980_spi0_probe: dma0chan3 module removed
    m25p80 spi1.0: unrecognized JEDEC id bytes: ff, ff, ff
    m25p80: probe of spi1.0 failed with error -2
    VFS: Mounted root (jffs2 filesystem) on device 31:2.
    devtmpfs: mounted
    Freeing unused kernel memory: 124K
    [Mount JFFS2]: /dev/mtdblock2 --> /mnt/mtdblock2
    
    BusyBox v1.22.1 (2016-02-03 14:11:04 CST) built-in shell (ash)
    Enter 'help' for a list of built-in commands.

（代码已经添加了相关busybox，如果没有busybox需要自行裁剪）
根据上述代码可以看出，内核已经对空间进行了分配，根据需要分配成三个区，并将文件系统挂载到
（VFS: Mounted root (jffs2 filesystem) on device 31:2），
此处的device31:2是什么含义呢？如果挂载了文件系统，则可以看出此代码的含义为挂载在主设备号为31，次设备号为2的设备上，即经过分配的nor0的mtdblock2上。

复制代码

1
2
3
4
NUC980@root#ls -l | grep mtdblock2
brw-rw----    1 root     root       31,   2 Jan  1 00:00 mtdblock2
lrwxrwxrwx    1 root     root             9 Jan  1 00:00 root -> mtdblock2

4、如果内核裁剪不到位的话，可能会导致mtd分配失败，只要多设置几次，mtd一定会加载成功的，只要在内核的打印输出中出现如下信息，则代表mtd已经分配成功，可以进行文件系统挂载，在这里还是需要提醒大家，下载到的linux源代码还是尽量不要进行代码级别的修改，否则不是老鸟，出现错误无法查找。

到此移植内核已经完成了，如果有不清楚的可以留言，能回答的可会回复。