[U-Boot] Question: booting Linux from ext4 mmc partition

[nidalpres]

I did some more experiments and it looks like it has nothing to do with size.
I have created files of various sizes and loaded them all with no problems.
However, when loading linux kernel image, things break.
Contents of all files are just a lot of zero bytes.

Here is a sample session:
=> ls mmc 0:2 /boot
<DIR>       4096 .
<DIR>       4096 ..
<DIR>       4096 uboot
          102400 100k
          204800 200k
          307200 300k
          409600 400k
          512000 500k
          614400 600k
          716800 700k
          819200 800k
          921600 900k
         1048576 1M
         2097152 2M
         3145728 3M
         4194304 4M
         5242880 5M
         3656194 zImage_dtb
=> load mmc 0:2 ${loadaddr} /boot/5M
5242880 bytes read in 1798 ms (2.8 MiB/s)
=> load mmc 0:2 ${loadaddr} /boot/zImage_dtb
MMC0: Data error with command 18 (status 0xf0342020)!
 ** ext4fs_devread read error - block
=> ls mmc 0:2 /boot
MMC0: Command 16 timeout (status 0xf0244020)
** Can't read partition table on 0:0 **
** Invalid partition 2 **

I went on to use imx-bootlets to load kernel, since I'm working on
some user space code for now.
When I get around to do work on kernel space code I will come back to
u-boot and this issue.

Thanks for help and support.
Nidal.




On Tue, Jan 7, 2014 at 4:50 PM, Robert Nelson <robertcnelson at gmail.com> wrote:
> On Tue, Jan 7, 2014 at 1:26 PM, nidalpres <nidalpres at gmail.com> wrote:
>> Hi Robert!
>>
>> I have 4-5 microsd cards (Kingston, SanDisk, Samsung),
>> 4 and 8GB in size, tried two, same thing.
>>
>> I also tried vfat partition and disabled support for ext2 AND ext4
>> completely in u-boot, and basically same thing happened.
>>
>> Then I tried to list/load files manually from vfat/ext4 partitions
>> using u-boot command prompt. I can list vfat and ext4 partitions
>> and load files from them into memory.
>>
>> However, once I load uImage file everything regarding mmc access
>> and loading files breaks. I seems to me that loading one big file
>> somehow corrupts something (hahah, very precise explanation).
>> uImage is little over 4MB.
>
> So if it's a failing at 4MB, at what "size" does it work as you maybe
> over writing memory..
>
> Regards,
>
> --
> Robert Nelson
> http://www.rcn-ee.com/