• Registered: 2007-11-09
  • Posts: 59

Topic: acces loader partition

Hello,

Is possibe acces the mtd's bootloader partition?
Can i change the kernel command by this way?

I'd already change the kernel and filesystem, i add ext3 support, and i buil many applications using QT.
But i want to change the default root device to USB memory. How can i do that?


Best Regards

  • Registered: 2007-11-09
  • Posts: 59

Re: acces loader partition

I think is possible, when i run:

chumby:/# hexdump -C /dev/mtdblock0 |grep root                                 
                                               
00002bf0: 726f6f74 3d2f6465 762f6d74 64626c6f root=/dev/mtdblo                 
00002c00: 636b3320 726f6f74 66737479 70653d63 ck3 rootfstype=c                 
00002c20: 74747953 302c3338 34303020 726f6f74 ttyS0,38400 root                 
00002c40: 726f6f74 66737479 70653d63 72616d66 rootfstype=cramf

chumby:/# more /proc/mtd                                                       
dev:    size   erasesize  name                                                 
mtd0: 00100000 00004000 "Boot Loader"                                           
mtd1: 00200000 00004000 "PSP"                                                   
mtd2: 00280000 00004000 "Kernel2"                                               
mtd3: 00800000 00004000 "Root Disk2"                                           
mtd4: 00300000 00004000 "Kernel1"                                               
mtd5: 01600000 00004000 "Root Disk1"                                           
mtd6: 01800000 00004000 "Cache"                                                 
mtd7: 00080000 00004000 "MSP"

Can i rebuild the loader sources changing in bootloader/setupKernel.c
void

setup_tags(void *parameters, int doUpdateBoot)

{

    setup_core_tag(parameters, 4096);       /* standard core tag 4k pagesize */

    setup_mem_tag(DRAM_BASE, 0x4000000);    /* 64Mb */

    // setup_mem_tag(DRAM_BASE + 0x8000000, 0x2000000); /* 32Mb at 0x18000000 */

    // setup_ramdisk_tag(4096);                /* create 4Mb ramdisk */

    // setup_initrd2_tag(INITRD_LOAD_ADDRESS, 0x100000); /* 1Mb of compressed data placed 8Mb into memory */

    if( doUpdateBoot )

      setup_cmdline_tag("console=ttyS0,38400 root=/dev/mtdblock3 rootfstype=cramfs");    /* commandline setting root device */

    else

      setup_cmdline_tag("console=ttyS0,38400 root=/dev/mtdblock5 rootfstype=cramfs");    /* commandline setting root device */



    setup_end_tag();                    /* end of tags */

}


to:
void

setup_tags(void *parameters, int doUpdateBoot)

{

    setup_core_tag(parameters, 4096);       /* standard core tag 4k pagesize */

    setup_mem_tag(DRAM_BASE, 0x4000000);    /* 64Mb */

    // setup_mem_tag(DRAM_BASE + 0x8000000, 0x2000000); /* 32Mb at 0x18000000 */

    // setup_ramdisk_tag(4096);                /* create 4Mb ramdisk */

    // setup_initrd2_tag(INITRD_LOAD_ADDRESS, 0x100000); /* 1Mb of compressed data placed 8Mb into memory */

    if( doUpdateBoot )

      setup_cmdline_tag("console=ttyS0,38400 root=/dev/sda2 rootfstype=ext3");    /* commandline setting root device */

    else

      setup_cmdline_tag("console=ttyS0,38400 root=/dev/sda2 rootfstype=ext3");    /* commandline setting root device */



    setup_end_tag();                    /* end of tags */

}

and then:


dd if=/mnt/usb/bootloader.img  of=/dev/mtdblock0      ?


Is necessary a 512 byte align in bootloader.img?

If the bootloader does't works how can i reflash him?
with the iMX21 boot process?
using JTAG?


Best Regards