Re: Coldfire uClinux boot with u-boot

Hi,

There are also an option for supporting u-boot parameters in kernel config.
Not sure if it helps.

Cheers


On Sat, Jan 12, 2013 at 9:38 AM, Steve deRosier <[email protected]> wrote:
> Hi all,
>
> I'm stuck trying to get Linux to boot from U-Boot on a Coldfire system and
> I'd love some ideas of what to try next.
>
> I'm upgrading a uClinux system from a 2.4 kernel to 3.3. Additionally I'm
> trying to upgrade the boot-loader from u-boot 1.1.6 to release 2012.07.  The
> board is based on a MCF5235EVB. I did the Linux upgrade first, and am
> successfully getting the existing system boot loader to boot my upgraded
> Linux 3.3 images. Now I've moved on to upgrading u-boot.
>
> I was able to get U-Boot to come up successfully and it recognizes my Linux
> image and a bootm command starts just fine.  It does the checks,
> uncompresses, and goes to boot.  I turned on the debug messages in U-Boot,
> so I get the "## Transferring control to Linux (at address 0x20000) ..."
> message, it goes and does the jump and then...nothing...
>
> Note that the exact same Linux image boots fine from 1.1.6.  My 1.1.6 can
> boot both the 2.4 legacy image as well as my new 3.3 image.
>
> Unfortunately I've got minimal visibility into the system (My BDM interface
> is being a PITA, I've got assembly-only stepping, using CodeWarrior!!@#!@$!,
> in flash only.  Pretty much nothing else is functioning right at the
> moment), so I've been relegated to debug-via-printf, which isn't terribly
> useful at the interface between u-boot and linux.
>
> Through reading code, I see a huge discrepancy between how 1.1.6 and 2012.07
> starts the kernel.
>
> 1.1.6 uses a line:
>      theKernel (linux_argc, linux_argv, linux_env, 0);
>
> 2012.07:
> /*
> * Linux Kernel Parameters (passing board info data):
> *   sp+00: Ignore, side effect of using jsr to jump to kernel
> *   sp+04: ptr to board info data
> *   sp+08: initrd_start or 0 if no initrd
> *   sp+12: initrd_end - unused if initrd_start is 0
> *   sp+16: Start of command line string
> *   sp+20: End   of command line string
> */
> (*kernel) (kbd, initrd_start, initrd_end, cmd_start, cmd_end);
>
> Clearly different... I'd assume that U-Boot's Linux starting magic is in
> sync with the current Linux kernel, but if that's the case, and these are
> actually as different as they appear, then the OLD U-Boot should have a
> problem starting the NEW kernel also.  For grins, I grafted on the old
> sequence code into the new U-Boot, but that (as expected) failed also.
>
> I looked at the Coldfire startup code and it looks like it corrosponds to
> the same comment in U-Boot, and interestingly it seems to discard the bd_t
> structure that's passed in first.
>
> So far I think I've figured this out:
> * The FDT isn't used on Coldfire targets.
> * The Coldfire code discards the bd_t data passed in through u-boot.
> * Something funky is going on keeping Linux from booting, and it happens
> early enough that I can't see it in printk-land.
>
> If it makes a difference, for some reason we load kernel at 0x20000 and jump
> to 0x20000. This is a legacy of the existing project, I've tried to change
> it to 0x0, but that didn't help either. I had suspected it had to do with
> where the old bootloader placed itself in RAM, but it shouldn't be an issue
> with the new bootloader.
>
> For reference:
> RAM: 0x00000000, 32MB
> SRAM: 0x20000000
> MBAR: 0x40000000
> Flash: 0xFFC00000, 4mb (second flash module at 0xFF800000, but U-Boot
> doesn't know about that one). Image is stored at 0xFFC40000 and uses an
> initrd romfs immedately after the kernel
>
> Basic setup and design is similar to the 5235EVB.
>
> CONFIG_UBOOT, MTD_UCLINUX and MTD_UCLINUX_EBSS are all Y.
>
> I've been bashing my head against this wall all week, so I'd love it if
> anyone's got some ideas.
>
> Thanks,
> - Steve
>
> 5235IWI> bootm 0xffc40000
> ## Current stack ends at 0x01f2ca2c *  kernel: cmdline image address =
> 0xffc40000
> ## Booting kernel from Legacy Image at ffc40000 ...
>    Image Name:   IWI 007
>    Image Type:   M68K Linux Kernel Image (gzip compressed)
>    Data Size:    2270515 Bytes = 2.2 MiB
>    Load Address: 00020000
>    Entry Point:  00020000
>    Verifying Checksum ... OK
>    kernel data at 0xffc40040, len = 0x0022a533 (2270515)
> ## No init Ramdisk
>    ramdisk start = 0x00000000, ramdisk end = 0x00000000
>    Uncompressing Kernel Image ... OK
>    kernel loaded at 0x00020000, end = 0x00470404
> ## cmdline at 0x01f2c520 ... 0x01f2c520
> ## kernel board info at 0x01f2c4e0
> memstart    = 0x00000000
> memsize     = 0x02000000
> flashstart  = 0xFFC00000
> flashsize   = 0x00400000
> flashoffset = 0x00000000
> sramstart   = 0x20000000
> sramsize    = 0x00010000
> mbar        = 0x40000000
> cpufreq     =    150 MHz
> busfreq     =     75 MHz
> baudrate    = 57600 bps
> ## initrd_high = 0xffffffff, copy_to_ram = 1
>    ramdisk load start = 0x00000000, ramdisk load end = 0x00000000
> ## Transferring control to Linux (at address 00020000) ...
>
>
>
>
>
>
>
>
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-- 
Quoc-Viet (Kevin) Nguyen
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