请教如何把rootfs从挂载在flash上改成挂载到ram上？

fire_vr

大侠好，

我目前用的是Qualcomm的MSM9x15平台，目前代码中使用的bootcmd为：
KERNEL_BOOT_OPTIONS ?= "root=/dev/mtdblock2 rw rootfstype=yaffs2 rootflags=tags-ecc-off console=ttyHSL0,115200 console=ttyHSL1,115200"

root是挂载在flash上的。
现在的需求要改成挂载到ram上，按照baidu的方法，我试着改了一下：
KERNEL_BOOT_OPTIONS ?= "root=/dev/ram0 rw console=ttyHSL0,115200 console=ttyHSL1,115200"
但是内核启动的时候报错说找不到rootfs，如下面的错误。

对这一块很陌生，请教如何改到挂载到ram上呢？
万谢！

1. List of all partitions:
   
2. 1f00            1024 mtdblock0  (driver?)
   
3. 1f01           20736 mtdblock1  (driver?)
   
4. 1f02           50688 mtdblock2  (driver?)
   
5. 1f03           40704 mtdblock3  (driver?)
   
6. 1f04          152576 mtdblock4  (driver?)
   
7. 1f05            5376 mtdblock5  (driver?)
   
8. 1f06            2304 mtdblock6  (driver?)
   
9. No filesystem could mount root, tried:  ext3 ext2 ext4 squashfs vfat btrfs yaffs yaffs2
   
10. VFS: Unable to mount root fs on unknown-block(1,0)
    
11. User configuration error - no valid root filesystem found
    
12. Kernel panic - not syncing: Invalid configuration from end user prevents continuing
    
13. [<c0014a44>] (unwind_backtrace+0x0/0xfc) from [<c0666ad4>] (dump_stack+0x20/0x24)
    
14. [<c0666ad4>] (dump_stack+0x20/0x24) from [<c06670dc>] (panic+0x94/0x1cc)
    
15. [<c06670dc>] (panic+0x94/0x1cc) from [<c08fae70>] (mount_block_root+0x1ec/0x238)
    
16. [<c08fae70>] (mount_block_root+0x1ec/0x238) from [<c08fb09c>] (mount_root+0xf8/0x11c)
    
17. [<c08fb09c>] (mount_root+0xf8/0x11c) from [<c08fb228>] (prepare_namespace+0x168/0x1c8)
    
18. [<c08fb228>] (prepare_namespace+0x168/0x1c8) from [<c08faa54>] (kernel_init+0x1ec/0x230)
    
19. [<c08faa54>] (kernel_init+0x1ec/0x230) from [<c000ee30>] (kernel_thread_exit+0x0/0x8)
    
20. Watchdog bite received from modem software!
    
21. modem subsystem failure reason: err.c:537:Error detected on remote processor..
    
22. subsys-restart: subsystem_restart(): Restart sequence requested for modem, restart_level = 1.
    
23. Kernel panic - not syncing: subsys-restart: Resetting the SoC - modem crashed.
    
24. [<c0014a44>] (unwind_backtrace+0x0/0xfc) from [<c0666ad4>] (dump_stack+0x20/0x24)
    
25. [<c0666ad4>] (dump_stack+0x20/0x24) from [<c06670dc>] (panic+0x94/0x1cc)
    
26. [<c06670dc>] (panic+0x94/0x1cc) from [<c0043e70>] (subsystem_restart+0x1e8/0x234)
    
27. [<c0043e70>] (subsystem_restart+0x1e8/0x234) from [<c0044484>] (restart_modem+0xb4/0xd0)
    
28. [<c0044484>] (restart_modem+0xb4/0xd0) from [<c0044734>] (modem_wdog_bite_irq+0x38/0x60)
    
29. [<c0044734>] (modem_wdog_bite_irq+0x38/0x60) from [<c00b1c94>] (handle_irq_event_percpu+0x98/0x2a4)
    
30. [<c00b1c94>] (handle_irq_event_percpu+0x98/0x2a4) from [<c00b1f04>] (handle_irq_event+0x64/0x84)
    
31. [<c00b1f04>] (handle_irq_event+0x64/0x84) from [<c00b4a3c>] (handle_fasteoi_irq+0xbc/0x120)
    
32. [<c00b4a3c>] (handle_fasteoi_irq+0xbc/0x120) from [<c00b1590>] (generic_handle_irq+0x30/0x40)
    
33. [<c00b1590>] (generic_handle_irq+0x30/0x40) from [<c000ed4c>] (handle_IRQ+0x70/0x94)
    
34. [<c000ed4c>] (handle_IRQ+0x70/0x94) from [<c00084b4>] (gic_handle_irq+0x48/0x60)
    
35. [<c00084b4>] (gic_handle_irq+0x48/0x60) from [<c0671300>] (__irq_svc+0x40/0x70)
    
36. Exception stack(0xcf02de48 to 0xcf02de90)
    
37. de40:                   0001f03a ffffffff 000006fc c0055848 00000000 0000012c
    
38. de60: 00000190 0000000a c0a31068 ceab515d c0925c68 cf02debc cf02de90 cf02de90
    
39. de80: c06671e8 c03521b0 20000013 ffffffff
    
40. [<c0671300>] (__irq_svc+0x40/0x70) from [<c03521b0>] (__delay+0x0/0xc)

复制代码

arm-linux-gcc

回复 6# fire_vr


    设置CONFIG_INITRAMFS_SOURCE路径不要使用打包好之后的，而是要使用源文件路径
不需要制作ram0 image，也不要在cmdline中设置"root="，另外cmdline中需要添加"rdinit=/sbin/init"

fire_vr

先自己顶一下

arm-linux-gcc

你的rootfs image有多大？

fire_vr

有大概36M。。。

arm-linux-gcc

[ 本帖最后由 arm-linux-gcc 于 2014-10-30 10:48 编辑 ]

我记得initramfs的size是有限制的，具体多少记不得了，36M的size应该是超了，如果不行就再裁剪一下（只保留必要的，把不必要的放到flash里去）


make menuconfig，配置如下
General setup
  [*] Initial RAM filesystem and RAM disk (initramfs/initrd) support
  ()    Initramfs source file(s)             填入你的rootfs源文件的目录地址
Device Drivers
  [*] Block devices  --->
    < >   RAM block device support    去掉这个选项



cmdline设置
"console=ttyHSL0,115200 console=ttyHSL1,115200 rdinit=/sbin/init"

fire_vr

谢谢！

我现在裁剪到2M左右了，现在的文件系统打包到Kernel里面，即改CONFIG_INITRAMFS_SOURCE：
CONFIG_INITRAMFS_SOURCE="/devdata/ykong/Rootfs/_install"

但跑起来的时候有下面错误：
我的ram0是在ubuntu上这样生成的，请问有问题吗？
sudo mknod ram0 b 1 0

error：
  #0: mdm9615-sitar-snd-ca鶹FS: Cannot open root device "ram0" or unknown-block(1,0): error -2
Please append a correct "root=" boot option; here are the available partitions:
1f00            1024 mtdblock0  (driver?)
1f01           20736 mtdblock1  (driver?)
1f02           50688 mtdblock2  (driver?)
1f03           40704 mtdblock3  (driver?)
1f04          152576 mtdblock4  (driver?)
1f05            5376 mtdblock5  (driver?)
1f06            2304 mtdblock6  (driver?)
VFS: Unable to mount root fs on unknown-block(1,0)
User configuration error - no valid root filesystem found

fire_vr

自己顶。。。